Having trouble with my Tzumi wireless mouse?

I recently bought a Tzumi wireless mouse to replace my old one. After reading through the instructions and finding the USB chip in the bottom, I set it up to charge for a while (roughly 2 hours) to make sure it had enough power for usage. Now, though, despite plugging the chip into a USB port, the mouse doesn't seem to actually work at all. I know it's charging because the light on the pad is green and the mouse itself light up to confirm that's charging (just as the instructions said) but after everything, I still can't actually use it? Is there something I'm missing about how to use it?