Recent Global Posts Feed Not Updating

The feed is not updating for several of the sources that are using it. For example, when one person views:

http://www.socialprofitmachine.com/feed/globalpostsfeed

It hasn't been updated since 3/4.

When I view it, it shows that it was updated 3/11.

How can I solve this?

(We are using QuickCache(Pro), although hopefully that isn't the cause of this problem)