First confirm that the PP is working. In windows go to devices and check that it's installed correctly and make note of the what the address is. That's the address you use in the configuration. If there are two address then you may have to try each one. Then try and see if the motos move. If they do not, then check and see if you have a signala comming out of ithe pp cable. If you ise a volt meter you should see a change in the voltage from high to low, or use a tester and see if any light scome on the tester.
I assume ou have all else configured correctly.
Post your XML file and someone will have a look.
What version of MAach are you using?
RICH