Which some computers could not be found in "Network Computers" Report but found in "Computer Summary" report?

 Hi,

I have a All-in-One Altiris Notification Server 7.5 (Virtual Machine) for PC inventory & software deployment with MSSQL database 2008 R2.

I would like to generate all discovered computer from "Network Computers" Report, thus I use the following report:

- Reports > Discovery and Inventory > Computers > Network Computers

However, 1 of a PC "OC11" I cannot search in this report. It only could be found in "Computer Summary" Report:

- Reports > Discovery and Inventory > Inventory > Operating System > Computer Summary

"OC11" just a normal PC with agent installed, why it could not be found in  "Network Computers" Report?

- Reports > Discovery and Inventory > Computers > Network Computers"

Screen (Same host, Not found in "Network Computers" but found in "Computer Summary" Report):

Thanks.