Cura wont print via usb

[mechanicmem 1]

Hello, I have a very strange problem, I just can't print directly from the program, when I start it it heats up the table normally, executes some preparation commands, but then it just stops suddenly, every time i try to print it stops in a different stage.

 

 

The strangest thing is that if i use the option to save and then open the print instructions (g-code file) on another program it prints normally, what could be happening?

 

By the way, the printer I use is a custom one.

 

Thanks!