3 conditions must be met to get the enable LED:

• The board must be properly powered.  Check the documentation on the board, as a misunderstanding on how it is powered is very possible.
• The board must be connected to a PC/Motion Controller which is connected to the power system.  The board has a ground detection circuit using pins 18 and 19 that disables the output is the board is not connected.  This is as a cable disconnect detection feature.  Check the cable.  There are some cheap cables out that that only use pins 1-17.
• There should be a jumper (or wired it parallel to e-stop) between the EN terminal and the +5vdc next to it.

• The SCHP must be disabled on the board or enabled and configured in the control software.