Help me using the invisible button to drag a movieClip

[michael1989]

Hi all.
i'm a newer with Flash MX.Please tell me how do solve this problem.
I want to use a invisible button to control a movieClip (drag it)
Here is my ActionScript Code for button:
on(press)
{
drag=true;
}
on(release)
{
drag=false;
}

And the code's attached to the movieClip:
onClipEvent(enterFrame)
{
if(drag)
{
this._x=_root._xmouse;
this._y=_root._ymouse;
}
}

And the result:NOTHING HAPPEN


please help me,thanks u alot.[/b]