Sorry for the delay in getting back to you.
To get the Debugging information I need, you will have to go to your Admin Control Panel.
Click on Site -> Global Configuration -> Debug Site (Yes)
Once you have done this, perform a search that should return a result from your forum. In the results page, there may be an error or warning at the top of the results section. Probably just a warning since an error would have shown up sooner usually. If there is such a message, I'll need that but it probably is an array_merge() problem... I have gotten these warnings from users before but that doesn't really tell me much. What I really need should be at the bottom of the page.
There will be a very long list of database queries at the bottom of the page. Don't worry, your queries won't show me anything I shouldn't see unless it is the debug information shown during a log in attempt. Basically, every little bit of information shown on your page as one or more database queries associated with it. I'll need to review those queries and determine what is going wrong with the system.
Even though your queries won't show me something that could cause a security risk, you probably shouldn't publicly post it so here is the link you can use to send me a personal message:
PM vujsa
Once I analyze the data, I can either fix the searchbot or tell you how to fix your system.
vujsa