Unable to add an rss to wp

trying to add this rss to wp.
in the widget area i added the rss widget to the sidebar.
I then added this ur.
I get the error message

RSS Error: This XML document is invalid, likely due to invalid characters. XML error: Reserved XML Name at line 1, column 39

have not added rss feeds before but i see no probs w/the urls and thought it would be pretty straight forward.

It’s not a fault on your side of things.

Well, ha! always love it when it is not on my side of things!
Any suggestions on how i could make it work?
do i need to tweak the url?