There should be a trim limiter. If the drive is all the way In (Down), then the trim up will give you about 5-6 'clicks' up. This prevents you from raising the drive too far Out (up) while in gear. The trailer button will raise it the rest of the way.
Try to trim in until it stops. Then try to trim out. If In works and Trailer works, but not Out, then it is more than likely the solenoid on the drive trim pump.