Problems with drop down menu need help

Hello I am new to Flash and to this wonderful forum now I have been trying to figure out how to make the this MC drop down menu to work. The stage size is 703 x 310 there is an upper menu bar totally designed with flash and a background which loads up as you roll over the buttons on the menu bar. the image that loads up is is the same width and almost the same height. on the inner mask I have an AS layer with stop(); on frame 1 and stop(); on frame 6 and gotoAndStop(1);on flame 7 this all done in the background mask. now the as scrip for the button of the menu bar are:

on(rollOver){
this.subGradMenumc.play(2);
}
on(rollOut){
this.subGradMenumc.stop(1);
}

and so on for all of the rest of the buttons however this is not working for me it works when I go slowly over and out of each one and when I move the cursor quickly over the bar everything loads and have tried it at home with CS3 and on a Mac so its definitely something that I am doing wrong. I donĀ“t know if i can load MC with buttons to work as a drop down menu. I am doing this for a University in Brasil and need to know if this will ever work or how to make it work I have spent the last 2 weeks trying to make this work and have not been able to do it, also I have searched high and low and tried several com combinations and I have come to you guys for possible assistance. thank you very much for your time and possible help.

here is the link: http://www.swfup.com/file/74048#view