I've installed MetaMask, connected to Ethereum Main Net and created an account. Then I copied the address of the account (did "Copy address to clipboard") and sent it to the person who was going to send me some ether. However he failed to transfer it, he was told that the address that I gave him doesn't exist or something.
I'm new to the crypto world and just need to get that Ethereum thing. What am I doing wrong? I've followed MetaMask tutorial step by step. Do I need to register that account, or activate it somewhere else, after I create it in MetaMask?