c# - WCF impersonation is not impersonating an administrator -

i trying use wcf remote user management things. , reusing code had on server 2003 box , worked fine, on windows 7 test box when check see if user called function administrator says not.

[operationbehavior(impersonation=impersonationoption.required)] public string setpassword(string username) {     windowsprincipal principal = new windowsprincipal(operationcontext.current.servicesecuritycontext.windowsidentity);     system.diagnostics.debug.print(windowsidentity.getcurrent().name);     system.diagnostics.debug.print(principal.identity.name);     if (principal.isinrole(windowsbuiltinrole.administrator))     {         //try         {             lock (watchdog.m_principalcontext)             {                 using (userprincipal = userprincipal.findbyidentity(watchdog.m_principalcontext, username))                 {                     string newpassword = createrandompassword();                     up.setpassword(newpassword);                     up.save();                     return newpassword;                 }             }         }         //catch         {             return null;         }     }     else          throw new system.security.securityexception("user not administrator"); } 

principal.isinrole(windowsbuiltinrole.administrator) returning false every time. both current identity , principal.idenity correct user impersonated. , user member of administrators user group.

i think has uac implemented in windows vista , up. issue because production machine going on win2k8-r2 box.

any suggestions on do?

take @ article, under section, "coping windows vista" , written article uac , checking admin privs programatically.