Change alpha of a movie clip on a seperate button rollover?

I am trying to change the alpha of a movieclip when a seperate button is in it's rollever state. My teacher has come up with some sort of actionscript but this doesn't appear to work. I was wondering if anyone could help me?
here is the actionscript i currently have:


function unistart(){ //uniform start
pants_mc._alpha=30;

}
unistart(); // sets movieclip to 30% alpha.
pants_btn.onRollOver=function(){ // when pants_btn is rolled over pants_mc alpha is set to 100%
pants_mc._alpha=100;
}
pants_btn.onRollOut=function(){ //On rollout pants_mc returns to 30% alpha
unistart();
}

can anyone explain why this doesn't work or suggest an alternative? thanks

The problem is right here

This assumes that pants_mc lives INSIDE pants_btn while unistart would appear to be looking for the mc as a sibling of the button. So try changing that line to

basically telling button to look for a mc by going up one level and then looking for a sister item called pants_mc

Otherwise the code looks correct assuming your using the right clip names.

thanks, its working fine now