Get serial number different for PPC2003 than WM5/5

I use the following code to get the serial number for my WM5/6 devices:

typedef int (__cdecl *MYPROC)(LPBYTE, DWORD, DWORD, LPBYTE, DWORD *);

MYPROC ProcAdd;

// Attemp to load aygshell.dll
HMODULE hLib = LoadLibrary(_T("coredll.dll"));
if (hLib)
{            
      ProcAdd = (MYPROC)GetProcAddress(hLib, _T("GetDeviceUniqueID"));

      if(ProcAdd)
      {

                   HRESULT hr = NOERROR;      
                    const GUID     bApplicationData1  = { 0x8d552bd1, 0xe232, 0x4107, { 0xb7,  
                             0x2d, 0x38, 0xb6, 0xa4, 0x72, 0x64, 0x39 } };
               const DWORD    cbApplicationData1 = sizeof (bApplicationData1);

       // Buffers to hold the two device IDs we are going to generate
      BYTE                g_bDeviceID1[GETDEVICEUNIQUEID_V1_OUTPUT];
      // Lengths of the returned device IDs
      DWORD               g_cbDeviceID1;

      g_cbDeviceID1 = GETDEVICEUNIQUEID_V1_OUTPUT;
      hr = ProcAdd (reinterpret_cast<LPBYTE>(const_cast<LPGUID>
                            &bApplicationData1)), cbApplicationData1,GETDEVICEUNIQUEID_V1,
                                 g_bDeviceID1,
                                 &g_cbDeviceID1);

      TCHAR        szDeviceID[(GETDEVICEUNIQUEID_V1_OUTPUT * 2) + 1];
            
      if (SUCCEEDED (DeviceID2String (g_bDeviceID1, g_cbDeviceID1, szDeviceID,
                                                                                                    ARRAYSIZE (szDeviceID))))
      {
            sSerialNo = szDeviceID;
      }
                  
}
else
{
      AfxMessageBox(_T("GetSerialNumber Error: ProcAdd NULL"));
      sSerialNo.Empty();

}

CloseHandle(hLib);

This works fine in WM5/6 but in PPC2003 it fails here:
ProcAdd = (MYPROC)GetProcAddress(hLib, _T("GetDeviceUniqueID"));
if(ProcAdd)
{
    blah blah
}

Why is this and how can I go about it?

Thanks