look at the code you inserted into the string, it isn't linking to a valid image link. this is the link you should have used:
http://img227.imageshack.us/img227/6217/dscf03496mx.jpg
and it should have looked like this:
edit: this is if you want to link directly to the image. why do you have to use HTML to link to a thumbnail? Just link directly to the image.