No value from PH Sensor UN0161 V2.0

Hello everyone, PH sensor with Arduino UNO.  What I tried so far. 

 

- Upload original test code from DFROBOT. - Tried reset EEPROM with DFROBOT code. Serial monitor showed 0:255
  1:255 2:255 3:255 4:255 5:255 6:255 7:255  - Tried again DFROBOT test code. Got this. _neutralVoltage:nan, _acidVoltage:nan
           temperature:25.0^C  pH:nan - Tried to change code of DFRobot_PH::DFRobot_PH() function. It seems to work for many but not for me. 

void DFRobot_PH::begin()
{   if (EEPROM.get(PHVALUEADDR, this->_neutralVoltage) == 0) {
       this->_neutralVoltage = 1500.0;  // new EEPROM, write typical voltage
       EEPROM.put(PHVALUEADDR, this->_neutralVoltage);
   };

   Serial.print("_neutralVoltage:");
   Serial.println(this->_neutralVoltage);

   if (EEPROM.get(PHVALUEADDR+4, this->_acidVoltage) == 0) {
       this->_acidVoltage = 2032.44;  // new EEPROM, write typical voltage
       EEPROM.put(PHVALUEADDR+4, this->_acidVoltage);
   };
      Serial.print("_acidVoltage:");
   Serial.println(this->_acidVoltage);

}

 

-  With the sensor in a glass of tap water, i get a calculated voltage between 1362 and 1372 but PH is        pH:nan

 

I try to calibrate using PH 4 solution and enterph but it does not recognize the solution.

 

Any other suggestions?  Thank you.