Im trying to post images from Flickr and im doing everything it says i should do, copy the URL and paste it in the "image" box and its not coming up and gives me the message "You are not allowed to use that image extension on this community." Picture Below showing eror message and what the image is supposed to look like.

That picture was imported from photobucket so i can do it with other image sharing sites accept Flickr and it would be loads easier for me to use that site as its linked with my iPhoto.
Any ideas on how to get it to not give me this image?
Extra info, Using macbook Pro, Lion OS, google Chrome
Cheers
Lewis