How to troubleshoot Inventory?

Please explain the Inventory process and how to troubleshoot it?

We were trying to use LanDesk 8.8 SP2 to query for Trend OfficeScan.  We were installing updates and wanted to know how many were left.

Well, my computer DEFINITELY has the new version, but the inventory doesn't find my computer.  The query is accurate, because it finds others with the same version.

I went and did a manual inventory on my machine, but it still doesn't show up in the query.

So now I am not trusting the inventory!

I have 666 in total machines, with over 100 (from what I can see) reporting incorrectly.

How do I find out what's wrong?

Thanks,

Scott.....