Sabertooth testing with arduino

Hi I've got problem getting sabertooth to run with arduino. But right now i'm testing the sabertooth with just potential metre, the sabertooth was on but the motor was not running.

Below are the images of my connection

http://img299.imageshack.us/img299/5557/60178438439426300637896.jpg

http://img571.imageshack.us/img571/7105/61100438441521300637896.jpg.

Im using a powersupply and drove it with 20v. The motor im driving is 24v 20A 180w hub motor.

Why are you trying to power a 24V motor with 20V? How much current is the power supply capable of delivering?