I bought a Dual Stepper Motor shield (ITEAD). I have hooked it up, checked and re-checked the wiring but I just get buzzing from both X and Y, when I use the test program. I set the pin call outs for X and then change them for Y. I get about the same thing for both of the two different stepper motors. I know that the motors work fine with other driver boards. I tried to tune the pot on the Y axis but that didn't help. There doesn't seem to be any difference when I plug in a 2 amp, 30 volt power supply. It does not run any better or buzz louder. I just get the same rhythmic sound like the motor is trying to turn.
In light of what I have done so far, what should I check first?