Analog input always zero

I really need help here.

My goal is to simply read analog values from the Arduino Mega using the "analog in" block. I know for a fact that the board physically works as I could read analog inputs using the Arduino IDE.

I am using the Arduino support package. Simulink returns a zero no matter what voltage I apply to the analog inputs. I am able to get PWM output working, so I know that the model is downloading to the Arduino Mega.