tanyakorteling on "MailChimp says RSS feed is invalid"

Hi;

I've been trying to set up an RSS feed campaign in mailchimp but it is saying the feed URL is invalid.

I've followed all the help advice given out and it seems that everywhere else the feed is valid:

I've tried the following:

http://www.cantravelwilltravel.com/index.php/feed/

Any ideas of how to fix this please?