problem with z-axis

Hi,
I have one big problem with my z-axis of my tuned Mendel90 LC with an E3Dv6 hotend and acrylic enclosure.
First of all, x- y- and z-axis could be homed and I manually can move the x-axis and the y-axis but not the z-axis!!
When I type the gcode G28 the z-axis homes, but if I try to move with G1 Z100 --- ther is no travel. No problems with G1 X100 or G1 Y100 , why this?
(configuration.h attached)
Manfred

Solved! The feedrate was set too high!
Manfred