Yeah, that won't work since you have to "Type in the URL to your custom avatar. The URL must start with http:// and the avatar must end in .gif, .jpg or .png. For example: http://www.example.com/avatars/avatar.gif", and yours has "https" instead of "http", and ends in ".net" instead of "gif, .jpg or .png".
You could put it in you "Sig" instead, asSpoiler: Insane Jeenyus