no upload to arduino when connected to RAMPS 1.4

Hello,
My problem is what the title of my topic says... I'm able to upload a sketch to my arduino mega 2560, but when I connect the RAMPS 1.4 to my arduino, impossible to upload... error message (Serial port COM13 already in use...) I tried with and without the connections on the RAMPS...
When I connect the RAMPS on the arduino, should led(s) blink or light on the RAMPS? Do I have to power the RAMPS independently as long as I'm just uploading to arduino?
Thanx
Regards
manu

That error means something else is using the serial port. Do you have something like printer face open? If not close everything else on your computer and try again.

Also are you sure com13 is the arduino?

thanks, I fixed this problem by buying a new RAMPS, now it works ...I have other problems but I'm going to create a new topic