EC sensor (K=1) coding problem

I have a problem with my code. I have this EC sensor with a temperature sensor both from DFRobot. I combined their codes given from manufacturer, installed the necessary library but I have always results for EC=0. I checked the connection and everything is OK.
Here is my code:

#include <OneWire.h>
#include "DFRobot_EC.h"
#include <EEPROM.h>

// Temperature sensor i/o
int DS18S20_Pin = 2; // DS18S20 Signal pin on digital 2
OneWire ds(DS18S20_Pin);  // on digital pin 2

// EC sensor i/o
#define EC_PIN A2
float voltage,ecValue,temperature = 25;
DFRobot_EC ec;

void setup(void) {
 Serial.begin(115200); // Baud rate: 115200
 ec.begin();
}

void loop(void) {
 // Read temperature
 float temp = getTemp();
 Serial.print("Temperature: ");
 Serial.print(temp, 2);
 Serial.println(" °C");

 // Read EC
 voltage = analogRead(EC_PIN) / 1024.0 * 5000; // read the voltage
 ecValue = ec.readEC(voltage, temp); // convert voltage to EC with temperature compensation
 Serial.print("EC: ");
 Serial.print(ecValue, 2);
 Serial.println(" ms/cm");

 // EC calibration process by Serial CMD
 ec.calibration(voltage, temp);          
 delay(1000); // Wait for 1 second
}

float getTemp() {
 // Returns the temperature from one DS18S20 in DEG Celsius

 byte data[12];
 byte addr[8];

 if (!ds.search(addr)) {
   // No more sensors on chain, reset search
   ds.reset_search();
   return -1000;
 }

 if (OneWire::crc8(addr, 7) != addr[7]) {
   Serial.println("CRC is not valid!");
   return -1000;
 }

 if (addr[0] != 0x10 && addr[0] != 0x28) {
   Serial.print("Device is not recognized");
   return -1000;
 }

 ds.reset();
 ds.select(addr);
 ds.write(0x44, 1); // start conversion, with parasite power on at the end

 byte present = ds.reset();
 ds.select(addr);
 ds.write(0xBE); // Read Scratchpad

 for (int i = 0; i < 9; i++) { // we need 9 bytes
   data[i] = ds.read();
 }

 ds.reset_search();

 byte MSB = data[1];
 byte LSB = data[0];

 float tempRead = ((MSB << 8) | LSB); // using two's complement
 float TemperatureSum = tempRead / 16;

 return TemperatureSum;
}