Running XP, Mach3, gecko G540.

So far, I've been successful at assembling my 4x4 CNC machine and getting it to run while connected to my Dremel tool which is manually switched on by me before running the gcode through Mach3:

http://www.youtube.com/watch?v=8QdbFP3t21A

I've been reading through the Mach3 manual and watching the videos, and see that I set some output signals to trigger a relay which can be used to turn the Dremel on and off.  I can see how this works, and it *looks* like it is working in the software.  However, my gecko G540 doesn't appear to do anything.  I have the two sides of my relay coil wired properly (one side to V+ and the other to terminal #5 on the G540), but the relay doesn't kick over when I click on the spindle control on the diagnostic tab in Mach3.  As I understand it, the port on the G540 drops to ground when the output signal (pin #17) is received, and because the other side of the coil is getting 48V+, this should kick the relay over.

I confirmed that I'm getting 48V+ from my power source.
I tested the relay itself and confirmed that it works with the power source.

So far, the hardware is in order.

So... software:  I wanted to test to see if I'm getting any kind of signal from pin 17 when I click on the spindle toggle on the diagnostic tab in Mach3.  My voltmeter jumps to 3.3v when I click the spindle toggle.   Is that enough?

Anybody familiar enough with the g540 to give me a rundown on why my relay isn't kicking over as expected?