iTunes is rejecting my podcast and I've troubleshooted everything I can think of

This is my feed: http://feeds.feedburner.com/PopCultureFMK

This is my WP: http://popculturefmk.wordpress.com

I have read every tutorial and I still get the message from iTunes that my cover art is not the right size (it is 1400x1400 just like it asks) and it says it must be hosted on a server that allows HTTP head requests. It's hosted on Libsyn, and I have done everything I can find to troubleshoot and I still can't figure out why iTunes is rejecting it.

HELP PLEASE!!!

on a Mac, using Chrome