Photo Gallery trouble

i’m a newbie in AS but i’m willing to learn and i’ve started to make my own flash site…made some simple motion tween, some buttons and then i wanted to make a simple photo gallery but using a transition effect by using action script cause this way i could make the transition backwards unlike using a motion tween that can only make the transition forward…
so googling i found this:
http://tutorialoutpost.com/view/4717/create-a-photo-gallery/
i saw that tutorial to work pretty well so i made a movie clip inside another movie clip inside my flash site and i repeated the tutorial above only this time on a movie clip and not on the main scene… and it just wont work…
the only thing i see is the blue shape that is under the mask and where the photos should appear…
any idea what i did wrong here??