Some registers are get read back some not of AD9106

Hello,

I am trying to generate sine waveform though DDS. I configure the register and try to read back, some registers are get read some not, on DAC no outputs come. Why these happened am using the SCLK 4MHZ and DAC clock is 150MHZ and tuning word is MSB and LSB is 0x003E 0x0A3D 0x003F 0x7100.