Problem with mic

pigasus89​ Sounds like you might be using a child account, (which is subject to a few limitations).

If you aren't using a child account, what settings do you have set up in-game, (and is your brother able to talk in-game as well)? Is your PC itself detecting your mic? (If you use Discord at all, are you lighting up green while talking in a voice channel?)

Note: I recommend that you both play on different PCs as if something were to happen, (such as one of you getting banned), it will affect both of you.