ActionScript 3.0 :: Common Library Fader MovieClip - Start Drag?

I'm using a common library fader movie clip. Inside the movie clip, is another movie clip called vertFader.

The code is simple.
vertFader.addEventListener(MouseEvent.MOUSE_UP, putDown);
vertFader.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
stage.addEventListener(MouseEvent.MOUSE_UP, putDown);
function pickUp(event:MouseEvent):void {
vertFader.startDrag(false, new Rectangle(-6.3, -50, 0, 100));
} function putDown(event:MouseEvent):void {
vertFader.stopDrag();
}

Here's my problem, everything works great except that vertFader doesn't drag. It will start the drag if I click it. It will also stop the drag if I click again. But if I click and hold the mouse button all day it will never start dragging. I'm not sure if it's a lag issue, or because I'm using a wireless mouse?