interuy on "RSS Error: This XML document is invalid, likely due to invalid characters."

Hi

I have this error message
RSS Error: This XML document is invalid, likely due to invalid characters. XML error: Invalid document end at line 11, column 49

The site is http://www.balkanscountries.info

I checked with http://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Fwww.balkanscountries.info%2Ffeed

http://validator.w3.org/feed/

But I can't found where is the problem.
I use another wordpress sites and haven't this issue

Any suggestion?

Thanks