ADS1299EEGFE-PDK: There is no signal when the electrode attached to skin with ADS1299

Edited version:
To read data, I am using this function. According to the status bits, it must return 0xC000. But when I try to read the stat_1 variable, it returns 0x00C0C0C0. 

/** @brief Read Data Continuous Mode
    *
    *
    @details After RDATAC command received by ADS1299, it starts with RDATAC.
    Go over channel by channel and read values.
    @details This function returns channelData
*/
void RDATAC_read_value(int32_t* channelData)
{   
    new_data_available = false;
    uint32_t stat_1 = 0x00;
    static uint8_t dummy_message = 0x00; // __attribute__((aligned(4))) = 0x00;
    static uint8_t inByte;//        __attribute__((aligned(4)));
    //int32_t channelData[8];       // __attribute__((aligned(4))) = {0};

    nrf_gpio_pin_clear(CS_PIN);

    for(uint8_t i = 0; i < 3; i++)
    { 
      spi_transfer_byte(&dummy_message, &inByte, 1);
      stat_1 = (stat_1 << 8) | inByte;
    }
    
    for(uint8_t i = 0; i < 8; i++)
    { 
      for(uint8_t j = 0; j < 3; j++)
      {
        spi_transfer_byte(&dummy_message, &inByte, 1);
        channelData[i] = (channelData[i] << 8) | inByte;
      }
    }
    
    nrf_gpio_pin_set(CS_PIN);
    
    for (int i = 0; i < 8; i++) { // Convert 3-byte 2's complement to 4-byte 2's complement
        if ((channelData[i] >> 23) == 1) { // Check if bit 23 is 1 (negative number)
            channelData[i] |= 0xFF000000; // Sign-extend by setting upper 8 bits to 1
        } else {
            channelData[i] &= 0x00FFFFFF; // Clear upper 8 bits for positive number
        }
    }

    new_data_available = true;
}