Instructions
Unplug the microphone from the "Rock Band" USB hub and reinsert the cord, making sure the connection is secure.
Examine the USB hub&'s power cord. See that the cord is firmly plugged into a power souce and the hub.
Check the Xbox 360 controller. A "Rock Band" microphone will not function without a connected controller. Make sure the batteries are charged.
Turn on "Rock Band," and test the microphone. If the device still does not work, unplug the USB hub and plug it into the other USB port on the console.
Test the microphone again. If it still does not function, unplug the USB hub and plug the microphone directly into one of the console USB ports. If the microphone works, there is a problem with the USB hub. If the microphone still does not function, the mic is the problem.