I have an odd situation. I bought three of the extracoreMD boards and have been playing with one on a breadboard. I can upload sketches using the arduino IDE to it using a Adafruit USB to ftdi TTL cable. It has worked fine for several weeks and in my troubleshooting today, still does. I'm now ready to move off the breadboard to a wired circuit. The only pin header is for the JP2 so I can plug the FTDI connector in. In my debugging I have one extracore with only the header soldered in. On my original board transmit and receive lights flash when the sketch is uploading. On the other two boards I only see the red transmit coming from the host.
The Arduino IDE give me this error
System wide configuration file is "C:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf"
Using Port : COM8
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x4e
Any ideas why one extracore board works and two won't take a sketch upload?