LTC6813 Configuration Problem

I encounter one problem with setting LTC6813 config registers.

I try to write config to LTC6813 IC and read it back, but the read back result is not match with what I written or default value.

Shown as following figure,

step 1 - I try to read back config setting after LTC6813 power up

step 2 - write config

step 3- read back config

My devices connection are PC <=USB=> DC2026C <=14-Pin Cable=> DC1941D <=IsoSPI=> DC2350A-B(IsoSPI-A)

Is there any problem with my connection or operation?