coustom data on AD9361 driver no_os not working

I am using zc702 with xilinx vivado platform to configure the ad9361 based FMCOMMS3 FMC.

when i am using the driver in the default state ,that is with function "dac_init(ad9361_phy, DATA_SEL_DDS, 1)" then i am able to get a sine wave with the set tone from the internal dds.

But when i disable the internal DDS using "DDS_Disable = 1 " on the axi_ad9361 ip, and then configuring the no_OS driver to DATA_SEL_DMA mode using the function "dac_init(ad9361_phy, DATA_SEL_DMA, 0)" I get no output the differential ports.

Can some one please explain why this is not working and let me know if i am missing any step.

FYI: I have removed the DAC_DMA and used and custom RTL logic to continuously send data to the axi_ad9361 ip.   

Thanks in advance.