SENO470 NOT WORKING with Arduino MEGA 2560 R3

When i copy and paste the code from DFRobot Website (https://wiki.dfrobot.com/SKU_SEN0465toSEN0476_Gravity_Gas_Sensor_Calibrated_I2C_UART)  for acquiring data in initiative mode, I receive the message “No devices” on my serial monitor.

I connected 

D/T on Smart Gas Sensor Terminal to A4 on Arduino Mega 2560 R3, 

C/R on Smart Gas Sensor Terminal to A5 on Arduino Mega 2560 R3, 

- (negative sign) on Smart Gas Sensor Terminal to GND on Arduino Mega 2560 R3, 

+ (positive sign) on Smart Gas Sensor Terminal to 5V on Arduino Mega 2560 R3.

Additionally, I set the DIP switch SEL on the Sensor to 0, A0 and A1 both to 0, to use I2C communication by default and then I copy and pasted the code for acquiring data in initiative mode.

However, I get message “No devices” on my serial monitor.

Below I pasted the image of the connection diagram from the DF robot website and Arduino MEGA 2560 R3 pinout diagram. The connection diagram is exactly the same, however, I am using Arduino MEGA 2560 R3.