An edit such as this one:
Images used in custom mood themes can either be uploaded to your ScrapBook or to a webspace provider that allows remote loading to LiveJournal. URLs for custom mood theme images cannot exceed 100 characters and it is necessary to set the height and width for each image.
Alternatively, on the create/edit http://www.livejournal.com/manage/moodthemes.bml page, a note saying that all three fields are necessary.
