Instructions
Verify that no other wireless headset devices are connected to Port 1 on your Xbox 360. No two wireless devices can connect to the same port on your console at the same time. If another player is in the room using a wireless headset that is connected to the machine, their headset is going to get priority versus the one that you are trying to connect at a later time.
Press the "Sync" button on your headset and then wait no longer than 20 seconds before pressing the "Sync" button on your console (or vice versa). If you're attempting to sync your headset to your console for the first time, you'll need to put both devices in pairing mode within a short time of each other. If you press the "Sync" button on the headset and then wait too long, the headset will take itself out of pairing mode by the time you press "Sync" on the console.
Charge your wireless headset's battery fully before attempting to pair it to your console. If your wireless headset's internal battery has a weak charge, it may have just enough energy to power itself on but not enough energy to actually be used or to be paired with the console. Charge your wireless headset's battery and then attempt to connect it to Port 1 on your console again.