EP-11S & GCP Partial 'Sweep'?

[EvilPhish]

Hard to really explain well, but I purchased a new 11 Rack and plugged it into my GCP and added a Mission EP-11S expression pedal.

Everything APPEARS to be ok, when I click the pedal the wah engages, pushing buttons on the GCP switches programs and all.

The problem IS, when I click on the wah with the EP-11S (and my toe is 'down' at this point) about 90% of the range of the sweep when I rock the treadle back does nothing at all, the final 10% of the rocking back suddenly sweeps the wah sound through it's entire range.

I've doublechecked my settings and I THINK I have everything correct. I've calibrated my expression pedal on the 11R, cables are in the correct spot, I have no idea what's going on. Help?

Edit: Polarity switch underneath the rocker. It's set by default to be plugged into the 11R even though it's made to interface with the GCP. Weird. Fixed. Thanks.