There have been a few questiosn like this lately..
first, is it a submitted diary? that'll lock you out (thank experimentgreen from last question)
also, it could be glitching, but that'd be more common.
i've also heard some people have problems uploading from safari on their phone? that may have been an isolated incident too.
maybe stupid question --> Did you verify your account email? most likely yes, but throwing it out there.
Contct GD customer support once you troubleshoot what you can..