LTC2500-32 :what's default value of Control Word??

i use LTC2500-32 and i want to use Control Word to set DF and filter type, and my set value of Control Word is 0x845,(DONT USE DGC,DCE,DF=4,filter type=SSINC)  BUT  after i  write this reggister, the 2500 don‘t  work anymore. actually,before i set reggister value,2500 can work,so i wanna know what's default value of Control Word? and why after i  write this reggister, the 2500 don‘t  work?  PS:  my PRE pin is low,and waiting for a control word to be shifted in at SDI on the first 12 SCKA clock pulses.