Hide a mc while RollOver button?

Hello campers!

I wanna make a mc that hide, while RollOver a button… is this possible?
I think it have to be something like this…

next_btn.onRollOver = function() {

			picMenu_mc._visible = 0;
};

//next_btn is the instance name of the button that I wanna rollover
//picMenu_mc is the instance name of the MovieClip i wanna hide

Any one who can say what Im doing wrong here?
Thanks!