That said, clicking on the picture allows me to go to the linked page, so all seems to be working for me (at least in the coded segment of your post).
Is it simply that it won't show in your signature or something? Obviously it's not there, but you said it dissapears from the preview area after a few seconds. can't be too sure why unless there's a problem with your account or sosmething that theadmins can look into. But if you can't see it in your coded area in your post above then I'd suggest a problem with your browser. What browser are you using?