I agree with Fly to Chill. The tail servo needs to be adjusted forward or backwards to correct tail wander. If you are interested in hearing more about this there are some nice HBK set-up videos on Youtube from subzzzzzzzero. Here is a link to the first one you can eaisly find the rest. Good luck.
http://www.youtube.com/watch?v=Dh30iHwx4GY