RTDX problems on 6437

I am trying to use RTDX to control actions in my target application from a Visual C++ program. I have followed all the instructions in the tutorials, and it is almost working. But I can't seem to get the correct data from the host to the target. I am reading in bytes from the host with the following code:

static int WaitingForRead = 0;

int32_T ReadRTDXByte(int8_T *RcvdData)
{
    int8_T data;
    int32_T status;

    // Request integer data
    if (!WaitingForRead) {
        status = RTDX_readNB(&ichan, &data, sizeof(data));
        if ( status != RTDX_OK )
            return 0;
    }
   
    // Check to see if channel has read data
    WaitingForRead = RTDX_channelBusy( &ichan );
       
#if RTDX_POLLING_IMPLEMENTATION

    // Make sure this is called in polling mode
    RTDX_Poll();
#endif

    // Check if data is ready and make sure it is the right size
    if (!WaitingForRead) {
        status = RTDX_sizeofInput(&ichan);
        if (status != sizeof(data))
            return 0;
        *RcvdData = data;
    }

    // Data has been properly transferred to output parameter
    return 1;
}

and in Visual C++ I am using this code to send the byte:

void CRTDXDlg::SendRTDXByte(char Data)
{
    long bufferstate; // holds the state of the host's write buffer

    m_Rtdx->WriteI1(Data, &bufferstate);
}

I am getting only 0 in the data byte at the target, no matter what I write to the host. The Channel Viewer shows the RReqCount and RByteCount as 1 and the XFRCount increments every time I send a byte, but 0 is the only value I receive. I have double checked the value that is being sent and it is not 0.

Does anyone have any ideas that might help here? Thanks in advance.