CHFARM Failed on Windows Server 2008

I got this issue when I want to perform change farm on one of my Citrix XenApp farms. The installed version is Citrix XenApp 5 for Server 2008. I have not encountered any issue before while using Windows Server 2003, so I believe this issue is somehow related to the differences between those 2 Windows versions, well, particularly the UAC. 

Issues :

• CHFARM utility failed in the middle, with below error :
  

Troubleshooting 

• It is due to UAC permission, it blocks CHFARM utility from properly running because it ran in Admin Approval Mode.

Resolution :

1. Go to Start > run, and type secpol.msc
   
   
   
    
2.  When you see this UAC permission control screen, choose I want to complete this action option, and press Ctrl + Alt + End as requested after that.
   
   
   
   
   
   
3.  Press Continue 
   
   
   
4.  Browse to Security Options as below
   
   
   
5.  Search for this option :

   

   User Account Control : Rul all administrators in Admin Approval Mode

   
   
6.  Right click at the option, and choose Properties
   
7. At here, choose Disabled,press Apply and OK
   
   
   
8. Below screen will explain why on this setting. Once everything is good, press Apply and OK.