ADS1298: Code problem

Hi: When i used ADS1298, after the initial flow after power up ,i read the  config register,and found the value is not correct, seen in the following figure ,the config2 register 's value is 0x00,and the correct reset value is 0x40,  strangely ,the other config register's value is correct, I don't know why?

                                                              FIGURE                            1

my initial code is :

ADS_START_LOW;  
ADS_REST_LOW;
ADS_CS_DISABLE;

ADS_REST_HIGH;
HAL_Delay(1); // delay 1ms
ADS_REST_LOW;
HAL_Delay(1);
ADS_REST_HIGH;
HAL_Delay(20);

ADS_START_LOW;
ADS_START_HIGH;

ADS_START_LOW;
adsSTART();
adsSTOP();
HAL_Delay(10);
adsSDATAC();
HAL_Delay(10);