prova così

on (press) {
onEnterFrame = function () { nomecaselladitestodi.scroll++;};
}
on (release, releaseOutside, rollOut) {
onEnterFrame = undefined;
}

al tasto per andare su invece


on (press) {
onEnterFrame = function () { nomecaselladitestodi.scroll--;};
}
on (release, releaseOutside, rollOut) {
onEnterFrame = undefined;
}