Game Help

Hey everyone,
My tutor at uni showed me this site, and its pretty awesome… but, onto the matter at hand.

I have to make a game using AS3 for my uni coursework and reached a point where I cant understand why it’s not working!

Its a multi-class version “remake” of a Zelda game.
Ive got the character on the stage, and moving around etc, thats fine, but I wrote an external class to handle what happens when he gets to certain points on the frame i.e.:
Collision, Changing frames etc, but for some reason this class is not being called, when its rather important for it to be called (obviously).

Any suggestions?
Want me to post code?

Thanks alot in advance for the help everyone!