Wireless SD Shield PWR LED flashing

I've just bought a BLEbee bluetooth thingy (this being the technical term), and tried plugging it into my wireless SD shield with a view to programming it. When I then power on the arduino, the red PWR led on the shield flashes. Without the BLEbee attached it doesn't.

Can anyone suggest to my what may be causing this? I've had a good search on the web but haven't found anything of use to explain the issue so far.

Thanks Jake