Your login name is not your callsign

These are two different names and mixing them up is the most common reason a sign-in fails.

• Your login name belongs to the account. It is 3-16 letters, numbers, underscores or hyphens, no other pilot ever sees it, and you can sign in with it or with your email address.
• Your callsign belongs to one pilot in one world. It is the name above your ship and in chat, and you choose it when you make that pilot.

Because a callsign belongs to a pilot rather than to you, the same account can carry different callsigns in different worlds. See Worlds, pilots, and what does not move.