Can't validate podcast from soundcloud to itunes. RSS issue.

Hi,

I've been trying to upload my podcast from soundcloud to itunes but this messages keeps appearing:

"Can’t download episodes from your feed. Podcast artwork must be between 1400 x 1400 and 3000 x 3000 pixels, JPG or PNG, in RGB color space, and hosted on a server that allows HTTP head requests". My artwork is 1400 x 1400 so I'm unsure what the issue is.

Below is my RSS feed.

http://feeds.soundcloud.com/users/soundcloud:users:223510893/sounds.rss

If you could assist me I would appreciate it. Thank you!