Calling a movie clip

Simple task, its just not working.

I have a button on the Main scene that calls a movie clip that contains 4 images in a row. Its masked so that only the image called in the script will be centered, blacking the others out.
I have an actions layer, a label layer, and a main layer with the movieclip on it.
The movieclip is called MainPicsMC.

So the code on the button is just this.
on (release) {
MainPicsmc.gotoAndPlay(“Castner”);

*Casnter being the frame label i want it to go go
now the movie clip should just slide and then center on my friends picture, but nothing happens at all. Any ideas?