No valid device found_can't open com port

Ground Control Software APM Planner 2.0
1

I think my amp 2.6 is viable because it lights up when I plug it into the usb port. But when I try to download the firmware for the initial setup, I get the message
"Unable to open com port"

running a new iMac with osx mavericks os

Started downloading firmware.diydrones.com/Copter/st … Copter.hex
Finished downloading /var/folders/d7/940w3y6172b61r6z53kmw_800000gn/T/qt_temp.nM9234
Opening firmware file…
Hex file loaded: 233322 bytes
Unable to open COM port:

2

you need to select the COM port to right of the Firmware update page and not be connected over MAVLink in the far right, top corner.

3

I have another problem related to comport, when I connect ardupilot to the computer, with APM planner software, I face the error " No valid device found" on firmware upload comport.