Today, the Search Engine Roundtable has a post explaining that Google News only shows results for news articles up to thirty-days old. To access any older news content, you must use Google News Archive Search.
The thing is, not all Google News sources are included in Google News Archive Search. In fact, you must qualify your content by requesting that Google add you to this special index. Google is specifically looking for “historical content” for this index
Here is an example of the latest story indexed by Google News from Search Engine Land:
Search Engine Land is currently not in Google News Archive search, so we won’t come up for searches in that index, but many publications will.