rollOver button to keep rollingOver

Hi,
I have button that makes an object move (north east south west buttons) then the mouse rolls over.

[color=blue]on (rollOver){[/color]
[color=blue] object._y = object._y + 5;[/color]
[color=#0000ff]}[/color]
[color=#0000ff][/color]
[color=black]But this way, the object only does this one time. Untill you rollover again.[/color]
How do i get it to keep giving the action for aslong as the mouse is on the button?
([color=blue]gotoAndStop(1)[/color] on the next frame doesnt work)

Should be very easy, but cant figure it out myself.