"RSS Feed Error - Invalid Feed format - Could not parse RSS Feed. Please check your RSS Feed."
This indicates that your RSS Feed does not respect the standards of RSS feed formatting or that you do not use a supported RSS or Atom Version (RSS 1.0 or above, Atom 1.0 or above). Digesto requires a valid feed in order to parse content from it.
We've got a few tools that could help you figure out what's wrong and help you fix it - see the feed specifications article, or check out our toolbox for RSS feeds.