Abstract button question?

ok this is hard to word but ill try:

This is what i want: I have a button and when the mouse is over the hit area i want the button to play at a certain point within a movie clip, hence i have used instance names and frame labels. this is what the actionscript looks like on the button:

on (rollOver) {
third.gotoAndPlay(“port1”);
}

third is the instance name i have give the MC.
port1 is the frame label inside “third” i would like to play from…

both the button and the mc third are in seperate layers in the same keyframe in a movie clip called “main stage” which is placed on the root stage.

does that make sense? thanks.