How to export EC private key as PKCS#1 or PKCS#8 format from certificate store by CNG?

I tried to export private key from certificate store by CNG API. It work fine when export RSA private key, but failed in EC private key.

The code failed in NCryptExportKey() with 0x80090029.

Is there any document from MS said: Export EC private key not support? or any sample code?

Here is my code:

    NCRYPT_KEY_HANDLE       hKey = NULL;
    SECURITY_STATUS         secStatus = ERROR_SUCCESS;
    NTSTATUS                status = STATUS_UNSUCCESSFUL;
    DWORD                   dwKeySpec, cbData = 0, cbBlob = 0, KeyPolicy = 0;
    PBYTE                   pbHash = NULL, pbBlob = NULL;
    PCCERT_CONTEXT          pSignerCert = NULL;
    unsigned char           *MessagePrivKey;
    Struct_Return ExportMessage = { NULL, 0 };
    bool bStatus;

    pSignerCert = GetCert(MY_CERT_NAME);

    if (!CryptAcquireCertificatePrivateKey(
        pSignerCert,
        CRYPT_ACQUIRE_ONLY_NCRYPT_KEY_FLAG,
        NULL,
        &hKey,
        &dwKeySpec,
        NULL))
    {
        goto End;
    }

    if (FAILED(secStatus = NCryptExportKey(
        hKey,
        NULL,
        NCRYPT_PKCS8_PRIVATE_KEY_BLOB,
        NULL,
        NULL,
        0,
        &cbBlob,
        0)))
    {
        wprintf(L"**** Error 0x%x returned by NCryptExportKey\n", secStatus);
        goto End;
    }

    pbBlob = (PBYTE)HeapAlloc(GetProcessHeap(), 0, cbBlob);
    if (NULL == pbBlob)
    {
        wprintf(L"**** memory allocation failed\n");
        goto End;
    }


    if (FAILED(secStatus = NCryptExportKey(
        hKey,
        NULL,
        NCRYPT_PKCS8_PRIVATE_KEY_BLOB,
        NULL,
        pbBlob,
        cbBlob,
        &cbBlob,
        0)))
    {
        wprintf(L"**** Error 0x%x returned by NCryptExportKey\n", secStatus);
        goto End;
    }

I also tried to call NCryptSetProperty() before export, but it failed with 0x8009000b.

KeyPolicy =  NCRYPT_ALLOW_PLAINTEXT_EXPORT_FLAG | NCRYPT_ALLOW_EXPORT_FLAG;

    if (FAILED(secStatus = NCryptSetProperty(
        hKey,
        NCRYPT_EXPORT_POLICY_PROPERTY,
        (PBYTE)&KeyPolicy,
        sizeof(KeyPolicy),
        NCRYPT_PERSIST_FLAG)))
    {
        wprintf(L"**** Error 0x%x returned by NCryptSetProperty\n", secStatus);
        goto End;
    }