Named Pipe Security for Domain Users only...

I am creating a named pipe that I want to allow only domain users to access.  I have posted the code below that I am using.  When I run the application there are no exceptions, everything appears to run normally.  However, when I try to create a client for the named pipe, I always get and ERROR_ACCESS_DENIED Win32 error code.  If I create the security descriptor with a NULL ACL the application works properly.

Hopefully someone can help.

SID_IDENTIFIER_AUTHORITY      SIDDomainAuth = SECURITY_NT_AUTHORITY;            // The domain users authority
int            nSize;                                                // The size of the ACL

// Allocate memory for the security descriptor
m_pSD = (PSECURITY_DESCRIPTOR)LocalAlloc(LPTR,SECURITY_DESCRIPTOR_MIN_LENGTH);

// Check for allocation failure
if (m_pSD == NULL)
      ThrowPipeException("Failed to allocate memory for the security descriptor.",false);

// Initialize the security descriptor
if (!InitializeSecurityDescriptor(m_pSD, SECURITY_DESCRIPTOR_REVISION))
      ThrowPipeException("Failed to initialize the security descriptor.");

//      m_pACL = NULL;

// Allocate memory for the ACL
m_pACL = (PACL)LocalAlloc(LPTR,sizeof(ACL));

// Allocate and initialize a domain SID
if (!AllocateAndInitializeSid(&SIDDomainAuth,1,DOMAIN_GROUP_RID_USERS,0,0,0,0,0,0,0,&m_pSIDDomain))
      ThrowPipeException("Failed to allocate a domain user SID.");

// Calculate the size of the ACL
nSize = sizeof(ACL);
nSize += (sizeof(ACCESS_ALLOWED_ACE) - sizeof (DWORD) + GetLengthSid(m_pSIDDomain));

// Initialize the ACL
if (!InitializeAcl(m_pACL,nSize,ACL_REVISION))
      ThrowPipeException("Failed to initialize the ACL.");

// Add the appropriate access for the domain users
if (!AddAccessAllowedAce(m_pACL,ACL_REVISION,FILE_ALL_ACCESS,m_pSIDDomain))
      ThrowPipeException("Failed to grant access to domain users.");

// Check to make sure the ACL is valid
if (!IsValidAcl(m_pACL))
      ThrowPipeException("Invalid ACL.");

// Set the security descriptor's SACL
if (!SetSecurityDescriptorDacl(m_pSD,TRUE,m_pACL,FALSE))
      ThrowPipeException("Failed to set the security descriptor DACL.");

// Check to make sure the security descriptor is valid
if (!IsValidSecurityDescriptor(m_pSD))
      ThrowPipeException("Invalid security descriptor.");

// Initialize the security attributes
m_SA.nLength = sizeof(m_SA);
m_SA.lpSecurityDescriptor = m_pSD;
m_SA.bInheritHandle = FALSE;