How to use ADO to insert BYTEA data?

I try to write this code for postgresql (for mysql working fine):

try
     {
         m_pRecordset->AddNew();
        iTimes++;

         VARIANT bitdata[3];

         SAFEARRAY *psafe[3] = {NULL, NULL, NULL};
         SAFEARRAYBOUND  band[3];

            bitdata[0].vt = VT_ARRAY | VT_UI1;
            band[0].cElements = FreImgSize;
            band[0].lLbound = 0;
            psafe[0] = SafeArrayCreate(VT_UI1, 1, &band[0]);

            for (long iSize = 0; iSize < FreImgSize; iSize++)
            {
                SafeArrayPutElement(psafe[0], &iSize, &pFreImg[iSize]);
            }

            bitdata[0].parray = psafe[0];
            if (bitdata[0].parray != NULL)
            {
                m_pRecordset->GetFields()->GetItem("CapturePic")->AppendChunk(&bitdata[0]);
            }

When calling AppendChunk error occurs.
Please help me, thks!

peng