Push the pedal and nothing happens after changing out the motor

We have a 2006 electric Club Car DS. We attempted to upgrade the motor to a 48 V 10 HP motor. After doing so, we push the pedal and nothing. We took the new upgraded motor out and put the original motor back in the golf cart (which worked fine prior to switching), and we pushed the pedal again and nothing again. What could have happened or be happening to cause this? And how can I fix it?