Do you by chance use more than one computer to logon? There can be only one computer at a time logged in; and sometimes exiting the program or discarding a browser tab won't "take" with ancestry and they still think you are logged into a previous session on another computer.

At any rate, I suggest you call ancestry. They can tell if you are logged in by other means and reset your login, or otherwise help to troubleshoot login problems.

1-800-262-3787