Microsoft Baseline Security Analyzer

I am using Microsoft Baseline Security Analyzer Version 2.2 (2.2.2170.0) on MS Windows SBS 2011 domain controller

I am unable to scan domain clients having Windows 7 OS but can scan Windows XP clients

getting the following error:

Security assessment: Incomplete Scan
Computer name: domain\laptop7
IP address: 192.168.0.102
Security report name: domain - laptop7 (5-13-2011 9-29 PM)
Scan date: 5/13/2011 9:29 PM
Scanned with MBSA version: 2.2.2170.0
Catalog synchronization date:


  Security Updates Scan Results
      
         Issue:  Security Updates
         Score:  Unable to scan
         Result: Windows Update Agent is not supported on this operating system.