Have you adjusted the gain at all? It's kinda tricky getting the gain and proportional set. For me, I adjust the proportional until I have as little rotation as possible, stopping when it seems that continuing is having no effect. At this point I try to adjust gain starting in the middle I + or - depending on what the tail is doing at this point. If drifting, increase. If twitching, decrease. Use small increments on your adjustments and be patient. You will get it locked.