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/timthumbFMRTYF

Query String : w=200&h=150&zc=1&a=c&src=http://www.clausmetalli.com/img/galleria/servizi6.jpg
TimThumb version : 2.8.13