Raise and consume AttachedEvent on button click

Question

I am trying to raise a custom built attached event on a button click. If I add handlers in the code, they are hit when the button is pressed but if I use the event in a WPF Trigger for animation, it doesn't work.

The Triggers that use the custom Attached Event is defined in a ControlTemplate for a CustomControl.

The same code works for standard AttachedEvents like Grid.MouseDown.

What am I missing here ?

Thanks, Saad