Is user a member of Admin group?

I have code that finds out if the current user is a local administrator.
Apparently, if the user is a member of a domain group that has
administrative privileges, that code doesn't work.  Does anyone know how to
determine if a user is an administrator OF ANY KIND?

Here is the code I am using currently.

   function IsAdmin: Boolean;
      var
         hAccessToken: THandle;
         ptgGroups: PTokenGroups;
         dwInfoBufferSize: DWORD;
         psidAdministrators: PSID;
         x: Integer;
         bSuccess: BOOL;

      procedure CantGetAdmin;
         begin
         raise Exception.Create( 'Unable to determine if you have
Administrator authority.' );
         end;

      begin

//      result := True;
//      exit;

      if Win32Platform <> VER_PLATFORM_WIN32_NT then begin
         result := False;
         exit;
         end;

      Result := False;
      bSuccess := OpenThreadToken( GetCurrentThread, TOKEN_QUERY, True,
hAccessToken );
      if not bSuccess then begin
         if GetLastError = ERROR_NO_TOKEN then begin
            bSuccess := OpenProcessToken( GetCurrentProcess, TOKEN_QUERY,
hAccessToken );
            if not bSuccess then CantGetAdmin;
            end
         else CantGetAdmin;
         end;

      GetMem( ptgGroups, 1024 );
      try
         bSuccess := GetTokenInformation( hAccessToken, TokenGroups,
ptgGroups, 1024, dwInfoBufferSize );
         CloseHandle( hAccessToken );
         if bSuccess then begin
            AllocateAndInitializeSid( SECURITY_NT_AUTHORITY,
                                      2,
                                      SECURITY_BUILTIN_DOMAIN_RID,
                                      DOMAIN_ALIAS_RID_ADMINS,
                                      0,
                                      0,
                                      0,
                                      0,
                                      0,
                                      0,
                                      psidAdministrators );
            try
               {$R-}
               for x := 0 to ptgGroups.GroupCount - 1 do begin
                  if ( SE_GROUP_ENABLED = (ptgGroups.Groups[x].Attributes
and SE_GROUP_ENABLED ) ) and
                     EqualSid( psidAdministrators, ptgGroups.Groups[x].Sid )
then begin
                     Result := True;
                     Break;
                     end;
                  end;
               {$R+}
            finally
               FreeSid( psidAdministrators );
               end;
            end;

      finally
         FreeMem(ptgGroups);
         end;
      end;