I can't find any particular solution to this problem. I have a project that utilizes 2 Ardiuinos (Arduinii?) communicating via I2C. The project works fine, though when I tried to compactify the hardware, I came up with the idea of stacking the Arduinos with the stackable headers from Adafruit or wherever, though I only connected one side. The following pins are connected: Reset, 3V3, 5V, GND, GND, VIN, and analog0-5. All the digital pins and the RX/TX are NOT connected. My problem is that I can no longer upload software to the boards. I have to physically separate them in order to upload. This is annoying, since it means opening the case, disconnecting and removing the arduinos, unscrewing all the standoffs, uploading software, and then putting it all back together. How come I can't program them when they're stacked?