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/timthumbfEG8u0

Query String : src=http://www.tmatorino.com/proposta/img/azienda.jpg
TimThumb version : 2.8.13