A TimThumb error has occured

The following error(s) occured:

The remote file is not a valid image. Mimetype = 'text/html' File = /var/www/html/timthumb/cache/timthumb8KCwKj

Query String : w=640&zc=1&src=http://www.campingmolinoafuoco.com/gestione/uploads/photo/46878_11960066_1000886326609958_4286995112109696095_n.jpg
TimThumb version : 2.8.13