Rss error when check using validator checker

I want to make auto post to facebook using networkedblog.com.. and it required an url rss feed from my vanilla website.. but networkedblog.com said that my url feed found an error..
actually i didnt found any error when try to open it from direct url, you can check it also from this url http://gudangartikel.net/discussions/feed.rss
but when i try to check using Validator Checker http://validator.w3.org/feed/
it tells some error like this, you can see my screen shot

I need your help please..
actually i didnt found any error when try to open it from direct url, you can check it also from this url http://gudangartikel.net/discussions/feed.rss
but when i try to check using Validator Checker http://validator.w3.org/feed/
it tells some error like this, you can see my screen shot
I need your help please..
0
Answers
grep is your friend.
what should i to do?? @x00
grep is your friend.
grep is your friend.
thanks for your solutions dude..
grep is your friend.