SPI Chip Select Issue

I am using cRIO-9023 and Chassis 9112 with NI-9401 Digital I/O card for the SPI. I want to integrate the SPI GYRO sensor module but unable to make the Chip Select LOW. I am using the SPI_SINGLE_PORT_EXAMPLE have changed the RT controller to my desired controller and added the FPGA modules too. To start the SPI interface it is mandatory to make the CHIP SELECT  ACTIVE LOW so that the SCLK may be generated then a 8 bit data is written and then wait for the READ data, when communication is finished the Chip Select may go HIGH to end communciation.

I have read the document at URL: https://decibel.ni.com/content/docs/DOC-7945

but unable to make the chip select low, can somebody make me correction where I am making a mistake .

Thanks

Ather Iqbal