GridView.FindName does not work with Type Of System.Windows.Interactivity.InvokeCommandAction

[Vincent]

Hi, this is my Xaml for my RadGridView,
To use double click, i had to use i:Interaction.Triggers...

<telerik:RadGridView  x:Name="GridViewList"
ItemsSource="{Binding LstResidantSecuriteSociale, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding SelectedResidentSecuriteSociale, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
SelectionMode="Single"
AutoGenerateColumns="False"
GroupRenderMode="Flat"
BorderBrush="White"
ShowGroupPanel="False"
FrozenColumnsSplitterVisibility="Collapsed"
RowIndicatorVisibility="Collapsed"
IsReadOnly="True"
Height="auto">

<i:Interaction.Triggers>
    <i:EventTrigger EventName="MouseDoubleClick">
        <i:InvokeCommandAction x:Name="CommandeMouseDoubleClick" Command="{Binding Path=DataContext.CustomCommandModifierLigne, RelativeSource={RelativeSource FindAncestor, AncestorType=telerik:RadGridView}, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" />
   </i:EventTrigger>
</i:Interaction.Triggers>

   <telerik:RadGridView.Columns>

  </telerik:RadGridView.Columns>

</telerik:RadGridView>

 i want to find the invokeCommandAction and set property IsEnabled to false;

//Works in WPF, not with silverlight

System.Windows.Interactivity.InvokeCommandAction Commande = (System.Windows.Interactivity.InvokeCommandAction)radGridView.FindName("CommandeMouseDoubleClick");
//In Silverlight Commande = null;

Commande.IsEnabled = false;

Thx a lot for help!
Regards, Vincent.