implicit-style

Silverlight 4 - How can I change button background color when focused with an Implicit button style?

I'm having a great deal of difficulty trying to achieve something that should be trivial. I'm using an Implicit Button Style defined in a global XAML resource file. I just want to change the background color of the focused button to red with a ColorAnimation. I've tried a number of different combinations in Storyboard.TargetProperty and ...