I had a bit of an annoying waste of time today when I was hunting down the cause of the indexed_search extension not indexing a TYPO3 web site. 

The problem for me was that I had the cache disabled in my typoscript template.

It was set as:

config.no_cache = 1

And then changing it to the following fixed it:

config.no_cache = 0

After that, indexing worked just fine. I indexed the site and after all was indexed, I set config.no_cache back to "1" because I wanted caching to be disabled while I was developing my site.