Hi,I assembled my first ever 3d printer and double checked and everything seem ok . I perform height measurement,auto leveling, modify z

offset, store preheat pla. Everything works fine. When Iselect print kossel leveling test nothing happens ( gcod file) The same happens from cura via usb. Drivers installed correctly, flashed firmware but printing will not start. I have tried other models but the nozzle will not print. Can you help?Thank you