Getting Issue With Y Axis

[jefflee]

Hello all, I'm new in the 3d print world cause I bought my first 3d printer some days ago. I assembly the printer without any problems but when I connect it to pc I've got a problem: I open Repetier-Host Geeetech and if I try to move manually the extruder, i don't have a problem in the X and Z axis but I have a problem in Y axis in fact:
-if i push "home" button the motor round forward only one or two step then it stop.
-if I try to move the plate forward it will go without any problems but if i try to move back, it don't move.
-if i force back the plate, and than i try to move it forward or back with the pc program, it will work. but when the plate goes over the middle of the smooth rod, these problems start again.
The motor connection is ok, I checked it. I think it's not a block or problem of the pulley/belt because the motor don't try to move, simply it will not receives the command.

Thank you very much