commercial check ride in fs9.0

When conducting the check ride, I fail after completing the short field landing. The lady says that I did not maintain 25" manifold pressure during the climb. My question is this: During the initial climb, after about 5000ft, I am at full throttle and can no longer maintain 25" manifold pressure as altitude increases. So naturally, manifold pressure decreases below 25" once I reach full throttle and continue to climb.Am I doing something wrong during climbs and is there anyway to get past this part of the check ride? (I'm flying the baron).thanks.