Photoelectric Troubles

I'm trying to build a counter circuit with the sensor listed above. I hook it up to the 5V, gnd, and digital pin 3. It has a built-in LED and lights when they are looking at each other. I absolutely cannot get an output out of it on the serial monitor. I am using the program below. Any help?

int sensorPin = 3;
int ledPin = 13;
int sensorValue = 0;

void setup() {
pinMode(ledPin, OUTPUT);
Serial.begin(9600);
Serial.println("start");
}
void loop() {
sensorValue = digitalRead(sensorPin);
Serial.println(sensorValue);
delay(100);
}

Do you have a load resistor on the sensor out to +
You could turn on the input pull-up resistor.

LarryD:
Do you have a load resistor on the sensor out to +
You could turn on the input pull-up resistor.

So you're saying place a resistor in series with the 5v and the sensor? What would a recommended value be?

First try to see if turning on the internal pull-up resistor will work.
pinMode(sensorPin,INPUT_PULLUP); // in the setup function
OR
Place a 1K resistor from +5v to the O/P of the sensor.

LarryD:
First try to see if turning on the internal pull-up resistor will work.
pinMode(sensorPin,INPUT_PULLUP); // in the setup function
OR
Place a 1K resistor from +5v to the O/P of the sensor.

And that was it! Thank you!