Rotation and Matrices Help

Hello,

I am using Corey Oneil’s collision detection kit, but I am having a problem with rotation.

In my code I have:

myItem.rotationY = 180;

However, during a collision detection, having it rotated like this causes an error with this line:

transMatrix1.concat(currentObj.parent.transform.matrix);

The error is simply “Error #1009: Cannot access a property or method of a null object reference.”

I have not really worked with matrices and rotation so if someone could help me that would be great. Do I need to make a matrix rather than just doing the rotationY or should I change something else? I cannot manually change the movie clip because it throws off the animation and armatures.

Thanks.