no datas can be read from ad7730 datas, read

we use ad7730 in our weigh scale design,
the DOUT pin remain high all the time,
even when we try to read the Status Register with 2051.
we have checked  the  following pins ,
can not find out what is wrong with it.
AVDD        5V
DVDD        5V
DGND        0V
AGND        0V
REF IN (+) 2.5V     (CONNECTED TO AD780)
REF IN (-)  : AGND
POL ,SYNC ,RESET      5V
CS            0V               
MCLK IN /MCLK OUT         4.9152HZ
AIN2(+) ,AIN2(-) ,ACX,ACX(---)    :AGND
VBIAS     connect to  AGND vias a  capacitance  

I will really appreciate it if you can help us with the problem.