Tween Class Question

1

I have an animation that I want things to happen at a specific frame of the animation.

function filmography() {
    var wtransTween:Tween = new Tween(wtrans, "_x", Regular.easeOut, -800, 800, 30, false);
    wtransTween.onMotionChanged = function() {
        if (this.position=0) {
        }
        mission._visible = false;
    };
    wtransTween.onMotionFinished = function() {
        xml.load("icons.xml");
    };
}

This is the code I have. What I want to happen is that when the filmography button is pressed that a white box slides across the stage, when it is in a specific position, covering the whole section, the text (mission) goes invisible., then when it is done moving it will load the XML.

When I have this setup it says this
“256 levels of recursion were exceeded in one action list.
This is probably an infinite loop.
Further execution of actions has been disabled in this movie.”

Please help.