Use styles define in application resources - wpf

Question

I'm having problem using any styles that are defined in my Application resources in another classes. These are the contents of my App.xaml class. When I try to apply the TextBox class I get error: cannot find named resource "validationTextboxStyle"
<Application x:Class="ClientApp.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:extToolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit/extended"
StartupUri="LoginWindow.xaml">
<Application.Resources>
<Style x:Key="validationTextboxStyle" TargetType="TextBox">
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<DockPanel LastChildFill="True">
<TextBlock DockPanel.Dock="Right"
Foreground="Orange"
FontSize="12pt">
!!!!
</TextBlock>
<Border BorderBrush="Green" BorderThickness="1">
<AdornedElementPlaceholder />
</Border>
</DockPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Application.Resources>
<Application.MainWindow>
<NavigationWindow Source="Main.xaml"></NavigationWindow>
</Application.MainWindow>
I try to use the style in another window.
<Window x:Class="ClientApp.NewItem"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:validation="clr-namespace:ClientApp.ValidationRules"
xmlns:extToolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit/extended"
Height="520" Width="400"
WindowStartupLocation="CenterOwner">
<Window.CommandBindings>
<CommandBinding Command="ApplicationCommands.Save"
CanExecute="SaveCanExecute"
Executed="SaveExecuted" />
</Window.CommandBindings>
<Window.Resources>
</Window.Resources>
<TabControl Height="Auto" Name="tabControl1" Width="Auto">
<TabItem Header="General" Name="tabItem1">
<extToolkit:BusyIndicator x:Name="busyIndicator" Visibility="Visible">
<Grid Name="contentGrid">
<extToolkit:ChildWindow Name="generateWindowChild" IsModal="True" Height="222" Width="300" WindowStartupLocation="Center" Grid.Column="0" Grid.ColumnSpan="6" Grid.Row="0" Grid.RowSpan="10">
<Grid>
<TextBox Height="23" HorizontalAlignment="Left" Margin="12,14,0,0" Name="txt_password" VerticalAlignment="Top" Width="242" />
<CheckBox Content="Numbers" IsChecked="True" Height="16" HorizontalAlignment="Left" Margin="16,79,0,0" Name="chk_numbers" VerticalAlignment="Top" />
<Button Content="Generate" Height="23" HorizontalAlignment="Left" Margin="58,152,0,0" Name="btn_generatePass" VerticalAlignment="Top" Width="75" Click="btn_generatePass_Click" />
<CheckBox Content="Upper case letters" IsChecked="True" Height="16" HorizontalAlignment="Left" Margin="16,123,0,0" Name="chk_special" VerticalAlignment="Top" />
<CheckBox Content="Special characters" IsChecked="True" Height="16" HorizontalAlignment="Left" Margin="16,101,0,0" Name="chk_upper" VerticalAlignment="Top" />
<Button Content="Insert" Height="23" HorizontalAlignment="Left" Margin="145,152,0,0" Name="btn_InsertPass" VerticalAlignment="Top" Width="75" Click="btn_InsertPass_Click" />
<extToolkit:IntegerUpDown DefaultValue="8" Value="8" Height="25" Width="35" Visibility="Visible" Margin="88,46,145,115" Name="minUpDown" PreviewKeyDown="minUpDown_PreviewKeyDown" ValueChanged="minUpDown_ValueChanged" />
<extToolkit:IntegerUpDown DefaultValue="8" Value="8" Height="25" Width="35" Margin="0,46,24,115" Name="maxUpDown" PreviewKeyDown="maxUpDown_PreviewKeyDown" ValueChanged="maxUpDown_ValueChanged" HorizontalAlignment="Right" />
<Label Content="Min length:" Height="28" HorizontalAlignment="Left" Margin="16,45,0,0" Name="minLengthLabel" VerticalAlignment="Top" />
<Label Content="Max length:" Height="28" HorizontalAlignment="Right" Margin="0,45,69,0" Name="maxLengthLabel" VerticalAlignment="Top" />
</Grid>
</extToolkit:ChildWindow>
<TextBox HorizontalAlignment="Left" Style="{StaticResource validationTextboxStyle}" VerticalAlignment="Top" Width="120" Grid.Row="2" Grid.Column="2" Grid.ColumnSpan="2" LostFocus="TextBox_LostFocus">
<TextBox.Text>
<Binding Path="GroupName" UpdateSourceTrigger="LostFocus" Mode="TwoWay">
<Binding.ValidationRules><validation:ItemGroupNameValidationRule /></Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<TextBox HorizontalAlignment="Left" Style="{StaticResource validationTextboxStyle}" VerticalAlignment="Top" Width="120" Grid.Row="3" Grid.Column="2" Grid.ColumnSpan="2" >
<TextBox.Text>
<Binding Path="Title" UpdateSourceTrigger="LostFocus" Mode="TwoWay">
<Binding.ValidationRules><validation:ItemTitleValidationRule /></Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<TextBox HorizontalAlignment="Left" VerticalAlignment="Top" Width="120" Grid.Row="4" Grid.Column="2" Grid.ColumnSpan="2">
<TextBox.Text>
<Binding Path="username" UpdateSourceTrigger="LostFocus" Mode="TwoWay">
<Binding.ValidationRules><validation:ItemUsernameValidationRule /></Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<PasswordBox HorizontalAlignment="Left" Name="txt_itemPassword" VerticalAlignment="Top" Width="120" Grid.Row="5" Grid.Column="2" Grid.ColumnSpan="2" LostFocus="txt_itemPassword_LostFocus" />
<PasswordBox HorizontalAlignment="Left" Name="txt_ConfirmPassword" VerticalAlignment="Top" Width="120" Grid.Row="6" Grid.Column="2" Grid.ColumnSpan="2" LostKeyboardFocus="txt_ConfirmPassword_LostKeyboardFocus" />
<Button Content="Generate" HorizontalAlignment="Left" Name="btn_generateNewPass" VerticalAlignment="Top" Width="36" Click="btn_generateNewPass_Click" Grid.Row="6" Grid.Column="4" Grid.ColumnSpan="2"/>
<TextBox HorizontalAlignment="Left" VerticalAlignment="Top" Width="120" Grid.Row="7" Grid.Column="2" Grid.ColumnSpan="2" >
<TextBox.Text>
<Binding Path="Url" UpdateSourceTrigger="LostFocus" Mode="TwoWay">
<Binding.ValidationRules><validation:ItemUrlValidationRule /></Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<TextBox Height="80" Width="200" Background="White" VerticalAlignment="Top" HorizontalAlignment="Left" Grid.Row="8" Grid.Column="2" Grid.ColumnSpan="6">
<TextBox.Text>
<Binding Path="Note" UpdateSourceTrigger="LostFocus" Mode="TwoWay">
<Binding.ValidationRules><validation:ItemNoteValidationRule /></Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<ListBox Height="80" HorizontalAlignment="Left" BorderBrush="LightGray" Name="listBox_Roles" VerticalAlignment="Top" Width="200" Grid.Row="9" Grid.Column="2" Grid.ColumnSpan="4">
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsChecked}" Content="{Binding Title}" Checked="checkBoxChanged" Unchecked="checkBoxChanged"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Label Content="Group" HorizontalAlignment="Left" Name="label9" VerticalAlignment="Top" Grid.Row="2" Grid.Column="1" />
<Label Content="Title" HorizontalAlignment="Left" Name="label1" VerticalAlignment="Top" Grid.Row="3" Grid.Column="1"/>
<Label Content="Username" HorizontalAlignment="Left" Name="label2" VerticalAlignment="Top" Grid.Row="4" Grid.Column="1"/>
<Label Content="Password" HorizontalAlignment="Left" Name="label3" VerticalAlignment="Top" Grid.Row="5" Grid.Column="1"/>
<Label Content="Confirm Password" HorizontalAlignment="Left" Name="label7" VerticalAlignment="Top" Grid.Row="6" Grid.Column="1"/>
<Label Content="Url" HorizontalAlignment="Left" Name="label5" VerticalAlignment="Top" Grid.Row="7" Grid.Column="1"/>
<Label Content="Note" HorizontalAlignment="Left" Name="label4" VerticalAlignment="Top" Grid.Row="8" Grid.Column="1"/>
<Label Content="Roles" HorizontalAlignment="Left" Name="label8" VerticalAlignment="Top" Grid.Row="9" Grid.Column="1"/>
<Button Content="Create" Command="ApplicationCommands.Save" IsDefault="True" HorizontalAlignment="Left" Name="btn_CreateItem" VerticalAlignment="Top" Width="75" Grid.Row="11" Grid.Column="2"/>
<Button Content="Cancel" HorizontalAlignment="Right" IsCancel="True" Name="btn_CancelCreateItem" VerticalAlignment="Top" Width="75" Click="btn_CancelCreateItem_Click" Grid.Row="11" Grid.Column="3" Grid.ColumnSpan="2"/>
</Grid>
</extToolkit:BusyIndicator>
</TabItem>
<TabItem Header="Expiration" Name="tabItem2">
<GroupBox Header="Expiration Rule" Height="229" Name="groupBox1" Width="469" VerticalAlignment="top" HorizontalAlignment="Left">
<Grid Height="210">
<Grid.RowDefinitions>
<RowDefinition Height="66*" />
<RowDefinition Height="144*" />
</Grid.RowDefinitions>
<RadioButton GroupName="passwordExpiration" Content="Never" IsChecked="True" Height="16" HorizontalAlignment="Left" Margin="38,22,0,0" Name="radioExpiresNever" VerticalAlignment="Top" />
<RadioButton GroupName="passwordExpiration" Content="In" Height="16" Name="radioExpiresInDays" Margin="36,65,-36,129" Grid.RowSpan="2" />
<extToolkit:IntegerUpDown Name="expiresInDaysUpDown" Margin="152,61,232,127" Height="22" Grid.RowSpan="2"></extToolkit:IntegerUpDown>
<Label Name="daysRecurring" Content="Days" Margin="231,58,0,117" HorizontalAlignment="Left" Width="38" Grid.RowSpan="2"></Label>
<RadioButton GroupName="passwordExpiration" Content="On" Height="16" HorizontalAlignment="Left" Margin="38,38,0,0" Name="radioExpiresDate" VerticalAlignment="Top" Grid.Row="1" />
<extToolkit:DateTimePicker Name="expirationDate" Width="203" Height="21" Margin="152,40,102,83" Grid.Row="1"></extToolkit:DateTimePicker>
</Grid>
</GroupBox>
</TabItem>
</TabControl>