Problem with Adjusting Time in an Active Directory Domain

Hi,

Can anybody help me with automation of adjusting time across a domain?

I need to adjust the time of all of workstations and servers together which are members of the domain. I tried several way like group policy, registry, etc. but gain no success. I am really puzzled with the issue! Is there any clear specific procedure for adjusting time across an Active Directory domain? The Active Directory I am talking about is a Windows 2008 R2 one with a Windows 2003 additional domain controller which is not connected to the internet.

TIA

Bijan