Seededuino Power Supply Issues

My project has a seeeduino board with the brick shield on top. I’m using it to read the diffuse reflection IR sensor, and then manipulate a servo. It works fine when it is connected to the computer and receiving power through the USB port. However, I need it to work on battery power. I have the board installed on the 9V harness (also purchased here).

I move the little switch from USB to external power and plug in the battery. It doesn’t work properly. So I used the wall wart and little adapter (again, purchased here). It doesn’t work. I tried switching back to USB and plugging it in to another computer (without the sketch running, or the drivers installed). I also tried using a straight USB battery charger (like for a cell phone).

The 9V battery behaves a bit differently than the other power options. With the “wall” power, the LED on the back of the IR sensor flashing rapidly, and the servo “twitches” about midway through it’s stroke. It’s kind of freaky, so I unplug it pretty quickly in case I’m damaging something. When I use the 9V battery, it tries more weakly to operate the servo (in little spurts), but again seems unstable.

I plug it back in to the computer running the sketch, and it’s back to perfect operation.

Unfortunately, this project is a Valentine’s Day box that my son and I made for his school party this Friday. It senses the presence of someone, and then opens a door for them to put their Valentine inside. I don’t think I’m going to be able to drag my computer along with it!

Am I missing something obvious? Is there something I was supposed to do with the bootloader? This is my first Arduino experiment so I’m hoping it’s something very simple.