I am using my mega board * motorshield. When i these boards use with the jumpers on the motorshield VIN then is all OK but when i will use these boards with external power nothing happens. The jumpers on the setmotorshield are set in the PWRIN mode and 12v power to the motorshield. Becomes the megaboard then the power from the motorshield or must i give the megaboard separate power? Best regards, Jack.