That error indicates you are entering credentials for a different Steam account. You can verify this by logging out of bungie.net and then logging back in, but picking Steam as the account to log in with. Then enter your log in credentials. If you get a completely different Bungie.net profile then that means you have more than one Steam account and the one linked to your current profile is not the same account. You can use Steam's forgot password recovery to see all the accounts you have under one or more email addresses.