Avatar - Invalid URL?

I keep getting an Invalid URL message when I try to insert the following URL for my avatar - http://rfreschner.smug​mug.com/photos/5386441​3-S.gif. Can anyone tell me exactly what's wrong with this? Perhaps the "-S" at the end?

Perhaps too large a file?

It's 13k, which I believe is above the limit of 8k, but I thought that was only for images being uploaded not linked. I've seen avatars in excess of 20k and I assumed those were linked.

I think here the avatars have to be uploaded,. even if linked they get "installed" as it were..

A few have larger avatars.. but I'm afraid it's just the mods.. (whoever they may be)

Ok, just tried this one - http://rfreschner.smug​mug.com/photos/5386441​3-Ti.jpg - and got the same Invalid URL message. I downloaded this one and it's only 5k so it must have something to do with the name, which is a bummer because that's the way smugmug names the different sizes of an image.

P.S. - I went ahead and uploaded it and it worked fine. I have to adjust the size now though.