Make sure you check all settings in the BIOS that can possibly affect the keyboard. One of those may control it. On the other hand, it may be that the keyboard refuses to work in the BIOS because it was created that way. Or the USB port isn't getting enough power on boot to recognize the keyboard in time. Since non-wireless keyboards work, I would try another wireless keyboard, if you can buy from a retailer with a nice return policy.
Because different manufacturers have different ways to make wireless work, you may be best off contacting them if none of your troubleshooting works.