I just checked and you do have an album set up. Are you logged into the Galleries when you attempt to upload your pictures?
The other thing that might be causing problems is an issue with your session cookies....that is, you might log in, but then take too long before attempting to upload a pic before it times out and essentially kicks you out of 'logged in' status. Try deleting your browser's cookies, close your browser and then restart it and log back into the Galleries. That'll set a new cookie that might take care of the problem.
However, I'm only guessing here, since I don't recall anyone getting an error message like that before when they did have an album set up.

Let me know how it turns out so I can troubleshoot further if needed.