EMC-backlash compensation

Here's an EMC question for the more experienced ones- does the backlash
compensation really work? I can't seem to get it to do anything for my Z
axis. I put a dial on the axis, get 0.004" of backlash, go into
stepper.ini , go to AXIS 2 and change backlash to .004- then nothing
changes. I put in a negative sign, put in a larger value and still nothing
changes.
I assume that AXIS 2 is the Z axis. Please correct me if I'm wrong.
By the way, I'm happy as can be just to have 0.004" backlash in the tired
old mill/drill. The ballscrew did wonders for it and it runs as fast as
the table too.

Thanks,
Dan Falck