Button loses it's rollover functions

I have a movieclip that has a button symbol in it.

When it is a movieclip and I put this AS on it:
on (press,release) {

It works fine, but loses the button rollover qualities.

I tried turning the above into a button to remedy it , but then the rollover works BUT the AS doesn’t.

Please help, been pulling my hair out.

Thanks in advance.