There could be a couple of reasons, first of all, a retract servo moves 180 degrees, make sure that it is moving the 180 from the retract linkages being directly apart to near touching, that will give you the maximum throw. If you can't get them to go all the way up then, then you will have to get a longer servo arm to have the throw increased, basically, the width of the servo arm has to be the exact same from center of hole, to center of hole, as the stroke of the activator on the retract.

In other words, you need to measure the amount of travel on your retract from the full down locked position, to the full up locked position. Then you need a servo arm that is that same distance from the center of your holes on the arms that your ball links will go through.

Also, be sure that your retracts (gear, wheels, strut etc) are NOT binding on anything. Be sure the servo is free to move that whole distance, a retract servo will drain a battery VERY fast. Make sure nothing binds that could cause the servo to stall.