Using a DataTrigger in my Style - wpf

Question

I am trying to change the fill of a rectangle based upon a value in my ViewModel but despite having tried all the suggestions I have found online, it still isn't working.
The IsMouseOver trigger works fine but the DataTrigger is ignored despite the fact there is always either a 4 or 5 in my ViewModel property.
Could somebody show me where I may be going wrong?
Thanks.
This is my style:
<Style x:Key="FavouriteRectangleStyle" TargetType="{x:Type Rectangle}">
<Setter Property="Opacity" Value="1"/>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Rectangle.Opacity" Value="0.5" />
</Trigger>
<DataTrigger Binding="{Binding Path=Theme}" Value="4">
<Setter Property="Rectangle.Fill" Value="{DynamicResource content__star__hex646464__shadow}"/>
</DataTrigger>
<DataTrigger Binding="{Binding Path=Theme}" Value="5">
<Setter Property="Rectangle.Fill" Value="{DynamicResource content__star__favorit__hexebebeb__shadow}"/>
</DataTrigger>
</Style.Triggers>
</Style>
EDIT: So it seems that my Binding was incorrect due to my incorrect assumption that the DataContext of the UserControl is where I should direct the binding.
The Rectangle is in the template for a ListBox and has "Items" as it's DataContext so by changing the "Binding" it now works.
Many thanks for all assistance though:
SOLUTION:
<Style x:Key="FavouriteRectangleStyle" TargetType="{x:Type Rectangle}">
<Setter Property="Opacity" Value="1"/>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Rectangle.Opacity" Value="0.5" />
</Trigger>
<DataTrigger Binding="{Binding DataContext.Theme,
RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType=UserControl} }" Value="4">
<Setter Property="Rectangle.Fill"
Value="{DynamicResource content__star__hex646464__shadow}"/>
</DataTrigger>
<DataTrigger Binding="{Binding DataContext.Theme,
RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType=UserControl} }" Value="5">
<Setter Property="Rectangle.Fill"
Value="{DynamicResource content__star__favorit__hexebebeb__shadow}"/>
</DataTrigger>
</Style.Triggers>
</Style>

Answer 1

Change your TargetType="Rectangle"
Here is the code I used to test
<Style x:Key="FavouriteRectangleStyle" TargetType="Rectangle">
<Setter Property="Fill" Value="Blue"/>
<Setter Property="Opacity" Value="1"/>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Rectangle.Opacity" Value="0.5" />
</Trigger>
<DataTrigger Binding="{Binding Theme}" Value="4">
<Setter Property="Fill" Value="Red"/>
</DataTrigger>
<DataTrigger Binding="{Binding Theme}" Value="5">
<Setter Property="Fill" Value="Black"/>
</DataTrigger>
</Style.Triggers>
</Style>
And the implementation
<Rectangle Style="{StaticResource FavouriteRectangleStyle}"/>

Answer 2

Inside the constructor of your window or usercontrol what you haveused, you should set this.DataContext = this; Otherwise binding not properly worked for the corresponding window or usercontrol.

Answer 3

That probably because you miss to implement the INotifyPropertyChanged interface, update you Theme property to this:
private int _theme = 5;
public int Theme
{
get
{
return _theme;
}
set
{
if (_theme == value)
{
return;
}
_theme = value;
OnPropertyChanged();
}
}
and make sure your codebehind or your viewmodel is implementing the interface
public partial class MainWindow : Window,INotifyPropertyChanged
{
here a full working sample:
Title="MainWindow" Height="350" Width="525"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Window.Resources>
<SolidColorBrush x:Key="content__star__hex646464__shadow" Color="Red"/>
<SolidColorBrush x:Key="content__star__favorit__hexebebeb__shadow" Color="Green"/>
<Style x:Key="FavouriteRectangleStyle" TargetType="{x:Type Rectangle}">
<Setter Property="Opacity" Value="1"/>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Rectangle.Opacity" Value="0.5" />
</Trigger>
<DataTrigger Binding="{Binding Path=Theme}" Value="4">
<Setter Property="Rectangle.Fill" Value="{DynamicResource content__star__hex646464__shadow}"/>
</DataTrigger>
<DataTrigger Binding="{Binding Path=Theme}" Value="5">
<Setter Property="Rectangle.Fill" Value="{DynamicResource content__star__favorit__hexebebeb__shadow}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
<StackPanel>
<Rectangle Style="{StaticResource FavouriteRectangleStyle}" VerticalAlignment="Center" HorizontalAlignment="Center" Width="200" Height="100"></Rectangle>
<Button Content="Change Theme" Click="ButtonBase_OnClick"></Button>
</StackPanel>
and the code behind :
public partial class MainWindow : Window,INotifyPropertyChanged
{
private int _theme = 5;
public int Theme
{
get
{
return _theme;
}
set
{
if (_theme == value)
{
return;
}
_theme = value;
OnPropertyChanged();
}
}
public MainWindow()
{
this.InitializeComponent();
}
private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
Theme = Theme == 5 ? 4 : 5;
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}

Answer 4

Answer in EDIT part of original question. Thanks for all assistance