LTC2508-32 SDOA has no output

Hello,

       I have a problem using LTC2508-32.The chip's  22-bit no latency output has data output, but the 32-bit filter result has no output. In my design,RDLA is pulled down to GND, MCLK=1MHz, DF=256, each conversion period has a busy signal, but the DRL signal is pulled up every 65ms cycle (not consistent with the datasheet of every DF conversions cycle), and the SCKA signal is given after the DRL signal drop edge, and no data is output from the SDOA pin. The driver sequence has been written in accordance with the manual requirements and has been checked.Hope to get your reply!