Getting a 404 error when using the RSS feed

I am using the Recent Global Posts Feed for my school site. I am also using post indexer and show recent posts plugins. When I go to my feed:

I get a 404 error.

Secondly, using the RSS widget I get this page:

This also brings me to a 404 error.

Have I possibly configured these incorrectly? Thanks for your time. I follow about 520 student blogs with these tools. :slight_smile:s