they might have muted you. also, it could be your controller, which has happened to me with my mics, i just switch controllers and I am good. Just because your headset can send messages doesnt mean it's not faulty. It could be able to talk sometimes, this has also happened to me. Also, it can not be a child account and still have voice settings to friends only, or even off. if it is off, you still can send messages though. you can mute your mic accidently without having the mute button on. it is under the voice tab on the 360. If you need any other help send me a message, and also if it still isn't working after you do all this, just take it back for a new one. oh and also, the battery on your controller may be low.