MAX6675 thermocouple

i use code arisen from an articale "Heat Transfer Lab Kit using Temperature Sensor based Arduino TM for
Educational Purpose https://drive.google.com/open?id=1JRadYNkTzgHI5q_EWp4akC9OrXhr4CBs"in order to get dltaT. However, i get C1=0°C as i show in figure below. Please, how can resolve this problem?

code:

#include “max6675.h”
int thermoDO1 = 8;
int thermoCS1 = 9;
int thermoCLK1 = 10;
int thermoDO2 = 2;
int thermoCS2 = 3;
int thermoCLK2 = 4;
MAX6675 thermocouple1(thermoCLK1, thermoCS1, thermoDO1);
MAX6675 thermocouple2(thermoCLK2, thermoCS2, thermoDO2);
int vccPin1 = 11;
int gndPin1 = 12;
int vccPin2 = 5;
int gndPin2 = 6;
void setup() {
Serial.begin(9600);
// use Arduino pins
pinMode(vccPin1, OUTPUT); digitalWrite(vccPin1, HIGH);
pinMode(gndPin1, OUTPUT); digitalWrite(gndPin1, LOW);
pinMode(vccPin2, OUTPUT); digitalWrite(vccPin2, HIGH);
pinMode(gndPin2, OUTPUT); digitalWrite(gndPin2, LOW);
Serial.println(“MAX6675 test”);
// wait for MAX chip to stabilize
delay(500);
}
void loop() {
// basic readout test, just print the current temp
Serial.print("C1 = ");
Serial.println(thermocouple1.readCelsius());
Serial.print("C2 = ");
Serial.println(thermocouple2.readCelsius());
delay(1000);
}