clearInterval problem

hey guys i’m really dissapointed becouse of this problem and i really need to solve it.

ihave a circles menu that follows the move movement and i’m using the setInterval and clearInterval thing. the problem is i’m not able to clear my interval. i’m new to actionscript incase there’s better way to do this let me know thanks. and here 's my code ;

maskMc.onEnterFrame = function() {

var mouseListener:Object = new Object();
mouseListener.onMouseMove = function() {

mouse_mc._x = _xmouse;
mouse_mc._y = _ymouse;
};
Mouse.addListener(mouseListener);
if (mouse_mc.hitTest(this)) {

int_var = setInterval(chase, 0);

}

};

maskMc.onRollOut = function() {
clearInterval(int_var);

};

chase = function () {
_global.perc = Math.round(handle._x*200/rail._width);
var xMouse = _root._ymouse;
if (Math.abs(xMouse-handle._x)<1) {
handle._x = xMouse;
} else {
handle._x -= (handle._x-xMouse)/40;
}
};