Crazy - Mega 2650, can't upload sketch if connected to screw terminal board.

Thanks - I will give it a try.

I did a bit more research and found others with the same issue. Posted a link to a reference page below.

Reference page Serial - Arduino Reference

Just so I understand.... Pins 0 and 1 are reserved for serial communications? Would that be for USB? As in the same pins as used for data in the USB port?

In the reference link posted above it says there are 3 additional serial ports.

The Arduino Mega has three additional serial ports: Serial1 on pins 19 (RX) and 18 (TX), Serial2 on pins 17 (RX) and 16 (TX), Serial3 on pins 15 (RX) and 14 (TX).

Do I need to worry about these pins as well?