ActionScript 3.0 :: Movie Clip Is A Class But Can't Call It's Functions?

I have a document class that assigns some button on the stage an function.
  
I have 2 cards on the stage. They have their own class.
  
From the buttons script i can trace the cards and i get: [object MovieClip]
  
But I cannot call a function in them like card_0.flipUp();
  
it errors:
TypeError: Error #1006: dimMe is not a function.
  
the card class is public starts out like:
 
public class FlipCard extends MovieClip {
 
The function is public:
  
public function dimMe ():void {
this.alpha = .1;
}