A TimThumb error has occured

The following error(s) occured:

You may not fetch images from that site. To enable this site in timthumb, you can either add it to $ALLOWED_SITES and set ALLOW_EXTERNAL=true. Or you can set ALLOW_ALL_EXTERNAL_SITES=true, depending on your security needs.

Query String : h=73&src=http%3A%2F%2Fwww.cle-chocs.com.%2Fupload%2Fcourse%2F638578190b535.jpg&w=101&zc=1
TimThumb version : 2.8.13