Scrolling movieClip: Loop within set area?

programming flash
1

I’ve got a movieClip that’s scrolling across the stage that loops nicely (kinda like the many cloud animations out there).

I’ve set the clip up to stop it’s scrolling on a rollOver, and start up again on the rollOut.

My problem is that after the rollOut the loop doesn’t work. The movieClip just keeps travelling. Can anyone help me in terms of the code? Tnx

 
blue.onEnterFrame = function() {
blue._x -= 2;
if (blue._x<=-0) {
blue._x = 864;
}
};
 
blue.onRollOver = function() {
delete blue.onEnterFrame;
};
 
 
blue.onRollOut = function(){blue.onEnterFrame=function(){
blue ._x-= 2;}
if (blue._x<=-0) {
blue._x = 864;
}
};