TM4C123AE6PM: SPI_Transaction use as Slave

I'm having problems getting reply data from a Tiva acting as a slave device. I've configured the SPI port for blocking 16-bit word size. I'm not sure how the slave select line is handle in slave mode. Basically, i need to send a 16-bit command word to the slave device to control things. However some commands need to respond back with data requested from the slave. The code in my slave looks as follows:

for(;;)
    {
        ulReply = ulRequest = ulDummy = 0;

        transaction1.count = 1;
        transaction1.txBuf = (Ptr)&ulDummy;
        transaction1.rxBuf = (Ptr)&ulRequest;

        /* Send the SPI transaction */
        success = SPI_transfer(hSlave, &transaction1);

        if (!success)
        {
            System_printf("SPI slave rx failed\n");
            System_flush();
            /* Loop if error reading SPI! */
            continue;
        }

        uint8_t opcode = (ulRequest & SMPTE_REG_MASK) >> 8;

        if (opcode == SMPTE_REG_REVID)
        {
            /* ====================================================
             * SMPTE CARD REV/ID REGISTER (RO)
             * ====================================================
             */

            ulReply = SMPTE_REVID;

            /* Send the reply word back */
            transaction2.count = 1;
            transaction2.txBuf = (Ptr)&ulReply;
            transaction2.rxBuf = (Ptr)&ulDummy;

            /* Send the SPI transaction */
            success = SPI_transfer(hSlave, &transaction2);

            if (!success)
            {
                System_printf("SMPTE slave reply failed!\n");
                System_flush();
            }
        }
        else if (opcode == SMPTE_REG_GENCTL)

The master side is controlling the FSS manually on the main board. The slave card has the FSS configured for control by the SPI module.

static bool SMPTE_Read(uint16_t opcode, uint16_t *result)
{
    bool success;
    uint16_t txbuf[2];
    uint16_t rxbuf[2];
    SPI_Transaction transaction;

    /* Set the read flag to send response */
    txbuf[0] = opcode | SMPTE_F_READ;
    rxbuf[0] = 0;

    /* Send the command */
    transaction.count = 1;
    transaction.txBuf = (Ptr)&txbuf[0];
    transaction.rxBuf = (Ptr)&rxbuf[0];

    /* Send the SPI transaction */
    GPIO_write(Board_SMPTE_FS, PIN_LOW);
    success = SPI_transfer(handle, &transaction);
    GPIO_write(Board_SMPTE_FS, PIN_HIGH);

    /* Set the read flag to send response */
    txbuf[1] = opcode;
    rxbuf[1] = 0;

    /* Send the command */
    transaction.count = 1;
    transaction.txBuf = (Ptr)&txbuf[1];
    transaction.rxBuf = (Ptr)&rxbuf[1];

    Task_sleep(3);

    /* Send the SPI transaction */
    GPIO_write(Board_SMPTE_FS, PIN_LOW);
    success = SPI_transfer(handle, &transaction);
    GPIO_write(Board_SMPTE_FS, PIN_HIGH);

    if (success)
        *result = rxbuf[1];

    return success;
}

When the master sends a command that expects a reply, it immediately issues another read with dummy byte to get the data returned. However, the second SPI_transfer call returns zero from the transaction operation unless I added the Task_sleep() call between the two transaction on the master side. Any help would be greatly appreciated.

Bob