Instructions
Turn off the Wii. Disconnect and reconnect the USB wireless receiver from the USB port on the Wii. Verify that the USB wireless receiver is receiving sufficient power from the outlet it's plugged in to.
Move closer to the Wii. Remove any obstructions (such as walls if the Wii is inside an entertainment center) surrounding the Wii. Disconnect any other wireless peripherals.
Insert new batteries into the guitar. Turn on the Wii. Press the "Sync" button on the wireless adapter. Press the "Sync" button on the guitar. The guitar should respond to all commands within the "Rock Band" interface. If you are still experiencing problems with the guitar, the device may be faulty.