Stepper motors only turning one direction

Here is my setup:

Centent Cn0143 Microstepping drives (older geckos)
680oz Camtronics Steppers
24v power supply
PC with Mach2

My motors are only turning in one direction. The distance traveled
is perfect though. When I jog 1 inch left then 1 inch right, it
makes it 2 inches right...

I measured the signals coming out of the Parallel Port and I am
getting changes in the direction voltage.

Any advice?