I am a newbie to WordPress and I do not know php.
When I validated my rss feed, I received this message:
Avoid using elements in namespaces when there are already core elements that do the same thing.
The item contains an element that duplicates the semantics of the description element. Be advised that clients will behave unpredictably in the presence of such an element: some will prefer it over the description element, others will ignore it, and the behavior may depend on the order in which such elements appear in the item.
Select whether you want your feed to contains summaries (sometimes called excerpts) or full content (a.k.a. body).
Encode your selection as HTML.
Place the result in the item description element.
Remove other elements that provide the same function.
Also, when I used the excerpt option with the advanced post, it did not display. I published it. Why was that?