OpenProcessToken fails with Access is Denied Error

From: Manoj (m_s77@hotmail.com)
Date: 07/29/02 

From: "Manoj" <m_s77@hotmail.com>
Date: Mon, 29 Jul 2002 10:42:54 +0530

Dear All,

I am trying to get the Process Token of a process which is running under
another users context.

Process A : Service Application running under Administrator Account (Not
LocalSystem)
Process B : Application running under a Standard User account.

Priviledges held by Administrator

    SE_TCB_NAME
    SE_DEBUG_NAME
    SE_SECURITY_NAME
    SE_TAKE_OWNERSHIP_NAME
    SE_CREATE_TOKEN_NAME
    SE_ASSIGNPRIMARYTOKEN_NAME

I have modified the DACL of the Process B and given all rights to
Administrator.

 ea.grfAccessPermissions =
GENERIC_ALL|STANDARD_RIGHTS_ALL|SPECIFIC_RIGHTS_ALL;
 ea.grfAccessMode = SET_ACCESS;
 ea.grfInheritance = NO_INHERITANCE;
 ea.Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
 ea.Trustee.TrusteeForm = TRUSTEE_IS_SID;
 ea.Trustee.TrusteeType = TRUSTEE_IS_GROUP;
 ea.Trustee.ptstrName = (LPTSTR) pSidAdmin;

    err = SetEntriesInAcl( 1, ea, NULL, &pDACL );
    if ( err )
        Err( L"SetEntriesInAcl", err );

    err = SetSecurityInfo( hWriteDAC, SE_KERNEL_OBJECT,

DACL_SECURITY_INFORMATION|PROTECTED_DACL_SECURITY_INFORMATION,
                           0, 0, pDACL, 0 );

No Error occurs and Operation is completed successfully. Then I use
Duplicate Handle to get the handle to the process

   if ( !DuplicateHandle( GetCurrentProcess(), hpWriteDAC,
           GetCurrentProcess(), &hProcess,
           PROCESS_ALL_ACCESS|PROCESS_QUERY_INFORMATION, TRUE, 0 ) )
    Err( L"GetProcessHandle- AddAceToProcessDacl -DuplicateHandle" );

After that when I try to open the process token I get access denied error.

  if (!OpenProcessToken (hProcess, TOKEN_DUPLICATE, phToken))
   Err (L"GetProcessToken - OpenProcessToken - Client");

Am I missing something? I have also tried with setting the SACL with NULL
ACL but that also doesn't help.

Please help me out to get out of this obstruct.

Regards,

Manoj