Did you update the skin with the project open? That's usually what causes this. Save and close the project, quit jAlbum, launch it again, re-open the project, and make the album again. Still get the error?
No, it's actually good to know about these things. There is still a problem with updating a skin with an open project. We can't seem to track down why it's happening. David thought he had the problem cracked, but I suspected that it was still lurking out there.