Running a Operating System Report i get the following

Manufacturer Product Version Installations
Microsoft Windows 7 Professional Edition 6.1 3,413
Microsoft Windows 7 Professional Edition x64 6.1 2
Microsoft Windows Server 2003 5.2 1
Microsoft Windows Server 2008 Enterprise Edition (full installation) 6.0 1
Microsoft Windows Server 2008 Standard Edition (full installation) 6.0 2
Novell SUSE Linux Enterprise Server 10 (x86_64) 10 1
Novell SUSE Linux Enterprise Server 11 (x86_64) 11 3

How come i have 3413 Windows 7 Professional Edition 6.1 but its not listed in discored product in asset management?
I cant understand how the inventory can see what operating system the clients have but asset management cant

3 Primary Server running SLES 11.1 - Microsoft Sql - Zenworks 11.2.1