Self Test of ADIS16475

I write a software to do the self test of ADIS16475 for 30 ,100 and 1000 iterations after power ON in stationary. Self test is failed  3 ,9 and 42 times for 30,100 and 1000 iterations respectively. but IMU is working fine. My software flows as below.

1.SPI clock is initialized to 1MHz and filter control register was set to 6.

2.Enable self test through global command register.

3.50 msec delay is introduced(no operation by host controller)

4.Read the status register.

5. 50 msec delay is introduced(no operation by host controller)

6.Repeat 1 to 5 by no of iterations.

Please provide necessary conditions and software flow to do the self test.