calibrating cnc using nc studio

Hello friends.
I purchase 6090 cnc machine and I have problem calibrating it.
The polarity of the limit switches are all red in the I/O.
When I push the CALIBRATE button, the Z axis goes up about 5mm and stops.For every pushing- 5mm up ,until it reaches the limit switch.
Once it reaches, I got error message of limit switch, and I can not move z axis further unless I disable the limit switches.
Can anybody help me?

hi,

Were you able to solve this?
im using nc studio. my spindle runs for a few secs (5-10) and stops, during that my PC freezes and then i get notification about limit switch on.