It still keeps saying improper image. How annoying. Ah well, thanks anyway.
Are you trying to link or upload? Uploading isn't enabled, so it might be that; and linked images have a maximum size of 120×120px and 100KB (well, the decimal sort so actually 97K), and only jpg/jpeg and png are supported; external URLs must end with one of those extensions, so URL-shorteners probably won't work.