Since you obviously know how to get to the Customize Profile section (i peeked at your profile) go there again. And when you input the URL to the picture in your album make sure you're getting the entire URL. It should start with 'http' and end with '.jpg' or '.gif' depending on the file type.
If that doesn't work try creating an album not available to anyone, copying the picture into that one and shrinking the size of the picture. Perhaps the picture you're using is too large.
Also, check what file type the picture is. jpg, and gifs are useable, but i don't think png and bmp are. Those are my suggestions. If that doesn't work i'd suggest going to a mod or Robo.