Missing namespace for
This element is in a namespace, but you have not declared the namespace.
Declare the namespace at the top of your feed. For example, if you use
dc:date in your feed, you will need to declare the proper
dc namespace, like this:
<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/">
Check the full list of namespaces for the exact declaration you need.
Not clear? Disagree?
You might be able to find help in one of these fine resources.