z axis not moving more the .1mm (6 replies)

I am in the midsts of building my first reprap prusa i2. Every time I try to home of mor my Z axis past .1mm the axis does not move. It just makes alot of sound. I am using Pronterface and sprinter firmware. I can sucessfully move the Z axis up and down using the .1mm movement rate..

Any ideas on how I can fix this?