Some avatars showing, others not

Hello Jamie,

Firstly, thank you for creating such a great plugin!

I’m having a couple of troubles with my site https://www.documentarytube.com if you browse to documentary with comments you’ll notice that some of the avatars are being displayed, and others not (ie. https://www.documentarytube.com/the-century-of-the-self).

I’m using wordpress 3.2.1, I’ve already changed the permissions of the /cache directory to 777 and have checked that the image is present and loading correctly on my site which it is.

If I type in the generated image URL
(https://1.gravatar.com/avatar/385338817e4a0acd3ba3ecb7af2d7189?s=32&d=http%3A%2F%2Fwww.documentarytube.com%2Fwp-content%2Fplugins%2Frage-avatars%2Flib%2Ftimthumb.php%3Fsrc%3Dhttp%3A%2F%2Fwww.documentarytube.com%2Fwp-content%2Fplugins%2Frage-avatars%2Favatars%2F007-no-me-gusta.png%26w%3D32%26h%3D32&r=G)

it states the following:
The type of image you are trying to process is not allowed

(from URL: https://i1.wp.com/www.documentarytube.com/wp-content/plugins/rage-avatars/lib/timthumb.php).

Thanks again for any help you can offer,

Regards,
Paul

https://www.ads-software.com/extend/plugins/rage-avatars/