This may happen because you did not log in properly or your session timed out. Session timeouts occur when you stay on the same page too long.
You will also need to log in again if the MySoccerLeague.com server just restarted.
In either of the last two cases, if you were in the process of entering data and had not saved it, the data was probably lost.
To log in again, just click on "Log In" below.