Servo using Arduino Mega

Hi, I just bough two full rotation servos that seem to work like DC motors. I am trying to control them with an Arduino Mega. They turn right when the sent number is above 97, turn left when the number is below 97, and stop when i send 97 no matter what angle it is pointing. Both the servos react the same way, but if I hook up some older servos that I have (non full rotation) thewith the same code, it works perfectly. Is it a code problem or are the servos defective?

assuming that these are the servos sparkfun sells - have you tried adjusting the rest point?