WPF, Validation.ErrorTemplate and Windows Phone - wpf

Question

I'm develepoing a Windows Phone application, and I need to validate some user inputs in text boxs. Here the XAML of one of these textbox:
<TextBox
Name="times"
Grid.Row="1"
Height="80"
Text="{Binding UpdateSourceTrigger=Explicit,
Mode=TwoWay,
Path=orari,
ValidatesOnDataErrors=True,
ValidatesOnExceptions=True,
NotifyOnValidationError=true}"
TextChanged="TextBoxChangedHandler"
/>
Using BreakPoints I'm sure the IDataError finds the error, but the TextBox appereance doesn't change. I've read I should use Validate.ErrorTemplate in the XAML, but I don't find this option, pheraps it doesn't exist in Windows Phone? How can I do to change the style of the textbox if the input is not valid?
Thanks

Answer 1

Hard to tell from what you have posted, but here's an example of some of my code that does something very similar perhaps it can help you locate your error.
The style to be used by textboxes I want to be validated, gets a red box when an error has occurred.
<Style x:Key="ValidationTextBox" TargetType="TextBox" BasedOn="{StaticResource {x:Type TextBox}}">
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<Border BorderBrush="Red" BorderThickness="1">
<AdornedElementPlaceholder />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip"
Value="{Binding RelativeSource={RelativeSource Self},
Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>
The text box itself
<TextBox Style="{StaticResource ValidationTextBox}">
<TextBox.Text>
<Binding Path="Description" UpdateSourceTrigger="PropertyChanged">
<Binding.ValidationRules>
<rules:MandatoryInputRule ValidatesOnTargetUpdated="True" />
<rules:IllegalCharsRule ValidatesOnTargetUpdated="True" />
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
An example validation rule
class IllegalCharsRule : ValidationRule
{
public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
{
if (value != null)
{
string input = value as string;
if (input.Contains(",") || input.Contains("/") || input.Contains(#"\") || input.Contains(".") || input.Contains("\"") || input.Contains("'"))
return new ValidationResult(false, "Validation error. Illegal characters.");
}
return new ValidationResult(true, null);
}
}