Armature,
I can not tell from the picture but the C25 board actually needs power, and it can be down two different ways. If you move the jumps on the ESS to allow the power to flow through P1 and P2 then the C25 does get the required power, you can verify by using a meter between the Ground Terminals and the 5V terminal on the C25 board. If you forgot to adjust the ESS jumpers to allow that power to flow the motors will not move. Blockhead also mentioned you need to define the ESTOP, for testing you can just use a wire jumper from ground to the ESTOP pin, i defined mine as P15, you had to declare this inside of MACH4 under inputs. The second way to provide 5V power to the C25 board is to run the power directly into the GND and 5V terminals.
Russ