C# Active Directory Debugging Help

The code executes correctly when the C# program is run on Windows Server 2003: DirectoryEntrynewUSer = new DirectoryEntry(); ... [login to view URL]("AllowLogon", new object[] { [login to view URL](false) }); But causes an error when run in Windows XP: "Unknown name. (Exception from HRESULT: 0x80020006 (DISP_E_UNKNOWNNAME))" This code is to turn off the "allow terminal server logon" property on a new active directory user object. I am setting other properties on the user object and they seem to work fine, but I have problems just with htis one property. Deliverable for this project is either a successful code example to use to get around this problem, or general help with a series of posts to help overcome this problem.