How can jpegenc in DVSDK support grey interleaved

I want to use the example of jpegenc in dvsdk to transform a grey format (i get only Y from YUV) to a jpeg format, so i change the parameter 'chromaformat' from XDM_YUV_422ILE to XDM_GREY, but i can allocate and initialize image encoder on the engine.

WHY?. And how can i use grey format in jpegenc? 

the part of code is as follow:

#define HEIGHT         480
#define WIDTH          720
#define SCANS          4
#define QVALUE         73

#define CHROMAFORMAT   XDM_GREY

#define BUFALIGN Memory_DEFAULTALIGNMENT

Int smain(Int argc, String argv[])
{
    Engine_Handle ce = NULL;
    IMGENC1_Handle enc = NULL;
    IMGENC1_Params encParams;
    IMGENC1_DynamicParams dynParams;
    IMGENC1_Status imgStatus;
    FILE *in = NULL;
    FILE *out = NULL;
    String inFile, outFile;

    if (argc <= 1) {
        inFile = "../in.dat";
        outFile = "../out.dat";
    }
    else if (argc == 3) {
        progName = argv[0];
        inFile = argv[1];
        outFile = argv[2];
    }
    else {
        fprintf(stderr, usage, argv[0]);
        exit(1);
    }

    GT_0trace(curMask, GT_1CLASS, "Application started.\n");

    /* open file streams for input and output */
    if ((in = fopen(inFile, "rb")) == NULL) {
        fprintf(stderr, "ERROR: can't read file %s\n", inFile);
        goto end;
    }

    if ((out = fopen(outFile, "wb")) == NULL) {
        fprintf(stderr, "ERROR: can't write to file %s\n", outFile);
        goto end;
    }

    /* open the Codec Engine */
    if ((ce = Engine_open(engineName, NULL, NULL)) == NULL) {
        fprintf(stderr, "ERROR: can't open engine %s\n", engineName);
        goto end;
    }

    /* allocate and initialize image encoder on the engine */
    encParams.size = sizeof(IMGENC1_Params);
    encParams.maxWidth = WIDTH;
    encParams.maxHeight = HEIGHT;
    encParams.maxScans = SCANS;
    encParams.dataEndianness = XDM_DEFAULT;
    encParams.forceChromaFormat = CHROMAFORMAT;   
    enc = IMGENC1_create(ce, encoderName, &encParams);
    if (enc == NULL) {
        fprintf(stderr, "%s: error: can't open codec %s\n",
            progName, encoderName);
        goto end;
    }

    /* set the parameters for encoding */
    dynParams.size = sizeof(IMGENC1_DynamicParams);
    dynParams.numAU = XDM_DEFAULT;
    dynParams.inputChromaFormat = CHROMAFORMAT;
    dynParams.inputHeight = HEIGHT;
    dynParams.inputWidth = WIDTH;
    dynParams.captureWidth = 0;
    dynParams.generateHeader = XDM_ENCODE_AU;
    dynParams.qValue = QVALUE;

    imgStatus.size = sizeof(imgStatus);
    if (IMGENC1_control(enc, XDM_SETPARAMS, &dynParams, &imgStatus) ==
        XDM_EFAIL) {

        fprintf(stderr, "%s: error: could not set PARAMS: 0x%x\n", progName,
            imgStatus.extendedError);
        goto end;
    }

    /* ask the codec for buffer sizes - these are typically conservative */
    if (IMGENC1_control(enc, XDM_GETBUFINFO, &dynParams, &imgStatus) ==
        XDM_EFAIL) {

        fprintf(stderr, "%s: error: could not get BUFINFO: 0x%x\n", progName,
            imgStatus.extendedError);
        goto end;
    }
   
    /* allocate input, encoded buffers based on GETBUFINFO */
    inBufSize = imgStatus.bufInfo.minInBufSize[0];
    inBuf = (XDAS_Int8 *)Memory_contigAlloc(inBufSize, BUFALIGN);

    encodedBufSize = imgStatus.bufInfo.minOutBufSize[0];
    encodedBuf = (XDAS_Int8 *)Memory_contigAlloc(encodedBufSize, BUFALIGN);

    if ((inBuf == NULL) || (encodedBuf == NULL)) {
        goto end;
    }

    /* use engine to encode the data */
    encode(enc, in, out);

end:
    /* free buffers */
    if (encodedBuf) {
        Memory_contigFree(encodedBuf, encodedBufSize);
    }

    if (inBuf) {
        Memory_contigFree(inBuf, inBufSize);
    }

    /* teardown the codec */
    if (enc) {
        IMGENC1_delete(enc);
    }

    /* close the engine */
    if (ce) {
        Engine_close(ce);
    }

    /* close the files */
    if (in) {
        fclose(in);
    }

    if (out) {
        fclose(out);
    }

    return (0);
}

And the RESULT is

error: can't open codec jpegnec