Problem with scoping onMotionFinished

I’m having a bit of trouble figuring out why I can’t trigger the function playUntil, which is another private function in this class, in this snippet. This is all residing in a class, and I’m wondering if that is what is making things tricky. Any help would be great. I tried tracing out currentTween.obj as well as currentDestination, both of which return undefined. Any help would be tremendous.

*private function processListenerInfo( listenerInfo:String ):Void {
setCurrentDestinationTo( listenerInfo );
if (( currentDestination != currentLocation ) && (currentDestination)) {
currentTween = new Tween(chapterSpawnLocation, “_alpha”, Strong.easeIn, chapterSpawnLocation._alpha, 0, .4, true);
currentTween.onMotionFinished = function() {
playUntil( currentDestination );
}
}
*}