Movie clip problem (maybe glitch or bug in Flash MX 2004)

Hey guys Im been working on my game but also this has been a really big issue with flash MX 2004 so I would put in here instead. I have made a movie clip that runs perfectly on its own, using “this” that way so I can copy and use it over and over. Here’s the code:

onClipEvent (enterFrame) { = false;
if (_parent._parent.rc.hitTest(this.wall)) {
if ( {
if (_parent._parent.player.hitTest(this.dc)) {
_parent._parent.player._x -= 6;
_parent._parent.dr._x -= 6;
[COLOR=Red][COLOR=Black]if (_root.dir==1) {
if (_root.g.gameplay.g.ddd.hitTest(this)) {[/COLOR]
[COLOR=Black] _x += _root.speed;[/COLOR]
[COLOR=Black] }
[COLOR=Black] if (_root.dir==-1) {
if (_root.g.gameplay.g.ddd.hitTest(this)) {[/COLOR]
[COLOR=Black] _x -= _root.speed;[/COLOR]
[COLOR=Black] }

See everything works fine. The instance name of this movie clip is “wall”. When I copy it and paste again and rename it to “walla” the red part of the code wont work. I know everybody had a problem like this. SO then I decided to test it and delete the original movie clip “wall” and leave “walla” there and it still dosent work. So everytime I copy the movie clip I get a bad movie clip that wont work even though the code works properly on the original. And when I do place a new one from the libary it still does the same thing. So if I get rid of the original one and only use new ones, the code doesnt work any more. Lot of things like this has happen to me in flash mx 2004. Is this a glitch or just another thing where flash corrupts the file and I have to copy and paste everything to a new file and hope it works.