rollOver command error

I’m using actionscript 1.0 and 2.0 on flash Pro 8 and keep getting an error when I test the movie. Here is the error:

on (rollOver) {;

Error Symbol=menuback, layer=mask, frame=1:Line 1: Mouse events are permitted only for button instances
on (rollOver) {
Total ActionScript Errors: 1 Reported Errors: 1

Can someone please tell me what I’m doing wrong? I’ve tried to create this rollover navigation…starting over 6 times already. Is there different language/coding for 1.0 and 2.0? I don’t understand what I’m doing wrong.

Thank you