[gnea/grbl-Mega Issue#27] Problem to move stepper motor

Hi, i’m an italian guy and i building a homemade cnc with Arduino Mega2560 and driver Pololu MD09B mounted on shield. I bought that here (http://www.futurashop.it/shield-per-arduino-motori-stepper-in-kit-da-saldare-8190-stepshield?search=step%20shield). At this link technical documentation ad electrical circuit explanation.
I load with IDE this GRBL library but stepper motors not moving.
I try a simple sketch without library and in this case motors work fine.
My question: is possible than library have a wrong configuration for my hardware. You can drive me on correct way, I’m not an expert of electronics and i not understand very well the pins configuration of your library.
Thank you very much.
PS. Excuse my bad english but I’m at work and write speedy not to let me find out of my boss XD