I'm getting the following error when trying to use the search box on our DNN site:
No Index Found. Please Run The SearchSpider Again And Make Sure It Completes Succesfully. Sorry, no results were found for invite

Here's what I've tried so far:

DNN Version: 05.06.01 (238)

1. Followed the steps on:
   http://www.deutschnetnuke.de/AboutDot...
(found that link in Sebastian's post from 2005: http://www.dotnetnuke.com/Community/F... )

Now, all of the following statements correctly produce 0 rows:
Select * from SearchItemWordPosition
Select * from SearchItemWord
Select * from SearchWord
Select * from SearchItem

2. Went to Host -> Search Admin, and selected the "Re-Index Content" link.   I then rec'd a green checkmark with a "Content Reindexed" message.  Now the above select statements now produces many rows, but the original error still occurs.

Thanks for your time,
-Steve
 

I think we've found the solution.  It seems that child portals are not automatically added to the search indexer.  So the following steps mostly resolved our problem:

To enable the search box on each child portal:

1. Log in as Host or super user enabled acct
2. On the Host Menu, navigate to Host -> Professional Features -> SearchCrawler Admin
3. In the “URL(s) to Index:” Line, add the full url of the child portal
4. Then click the green plus sign to the right of that text box to add it.
5. Near the bottom of the page, click the “update” link.
6. Within x hours (as designated in the scheduler), you should see that portal start to give search results.

One slight drawback is that the search results are for all child portals (we have 50+), not specifically for that child portal.

Finally got it to work by going to Host > Scheduler > Click the pencil > and checking the "Yes" Schedule Enabled box > Update > Run Now. After that I checked the history and it appeared to start indexing.

This was on 5.6 Pro.