When attaching a message by using the Action.Target dependency property the Can + MethodName guard is not invoked. I have attached a solution which has two projects. One for silverlight and the exact copy for WPF. The silverlight version works as expected but the WPF version does not work. Under WPF the Can + MethodName gets invoked when using the underscore syntax with x:Name
Silverlight:
<!-- Works -->
<Button Content="Click Me" cal:Message.Attach="SayHello" cal:Action.Target="{Binding Child.Child}" />
WPF :
<!-- Works -->
<Button Content="Click Me" x:Name="Child_Child_SayHello"/>
<!-- Does not work -->
<Button Content="Click Me" cal:Message.Attach="SayHello" cal:Action.Target="{Binding Child.Child}" />
Daniel