[TYPO3] Indexed Search, limiting to specific categories

[David Lanier]

I would like to limit some search results to specific categories.  I 
have several indexing configurations set up.  They're working properly. 
  Pages are being indexed regularly by the crawler.  Doing a regular 
search displays results that were indexed by all index configurations.

What I want to do is add another indexing configuration, and have the 
ability to include or exclude its records from search results.

The indexed search document (doc_indexed_search) gives these examples to 
enable grouping:

plugin.tx_indexedsearch.search.defaultFreeIndexUidList = 0,6,7,8
plugin.tx_indexedsearch.blind.freeIndexUid = 0

(I think that the "0" means "everything")

And for limiting to specific categories, the document suggests this:

index.php?id=78&tx_indexedsearch[sword]=level&tx_indexedsearch[_freeIndexUid]=7,8

the important part being:
&tx_indexedsearch[_freeIndexUid]=7,8

My Indexing Config IDs are 1,2,3,4,5,6,7,8.

I have added this typoscript to test search page:

plugin.tx_indexedsearch.search.defaultFreeIndexUidList = 8,7,6,5,4,3,2,1,0
plugin.tx_indexedsearch.blind.freeIndexUid = 0

I view that search page from the frontend by this URL:
index.php?id=1234&tx_indexedsearch[sword]=contact&tx_indexedsearch[_freeIndexUid]=8,7,6,5,4,3,2,1

The search results displayed are only eight headers (one for each 
indexing config requested by the URL) with "No results found." under 
each header.

I get the same result when I try fewer numbers too.
&tx_indexedsearch[_freeIndexUid]=4,3,2,1
&tx_indexedsearch[_freeIndexUid]=8,7,6,5

But of course, what I'm expecting are results that are limited the 
indexing configurations specified in the URL.

When I remove the numbers from the end, or the _freeIndexUid variable 
completely, I get a lot of results from all over the site.
index.php?id=1234&tx_indexedsearch[sword]=contact&tx_indexedsearch[_freeIndexUid]=
index.php?id=1234&tx_indexedsearch[sword]=contact

Does anybody have any suggestions as to what I might be missing?

Thanks in advance,
David Lanier