Prusa i3 build, help needed!

Hi everyone,
I recently finished the mechanical build of my prusa however I seem to have hit a brick wall with the electronics!


When attempting to jog axis small amounts the stepper motors usually judder however when trying to move large distances i usually get nothing but whining.
I've calculated the steps per mm using Josef Prusas calculator as well as trying the cooking hacks firmware, i've tripple checked the pots on the stepper motor driver's (All read 0.4v which i believe is correct?) and swapped them all around aswell as rewiring it several times. If anyone has any suggestions at all they would be greatly appreciated!
Thanks Oliver

Try upping the voltage on the stepper driver. Each motor is different and has a current rating. There is a way to calculate the vref if you have all the specs, but it is just as easy to turn one up until it moves reliably

Just fyi, the vref voltage on my steppers is .93

This page has the technicals on how to adjust if you have the motor specs
[reprap.org]

I also noticed in the pic, you do not have any stepper motor wires connected to the Y Stepper Driver perhaps check your wiring