IR Reflectance Sensor issues

I have 3 of the QTR-1RC IR Reflectance Sensors. The object is to use them for edge detection to prevent unwanted use of stairs. I snagged some code from one of the other forums and appear to have it hosed somehow. It all works but fails to return appropriate values. With a max value of 1023 per sensor, all I get is zeroes. (“0 0 0”)
I’ve included my purloined and slightly modified sketch below:

#include <PololuQTRSensors.h>  
int ledPin = 13;

// create an object for your type of sensor (RC or Analog)  
// in this example we have 3 sensors on analog inputs 3,4, 5, a.k.a. Arduino 
// digital pins 17 - 19

PololuQTRSensorsRC qtr((unsigned char[]) {17,18,19}, 3);  // edit to adjust for the
                             // number of sensors and desired Arduino pins for connections
void setup()  
  pinMode(ledPin, OUTPUT);
  // start calibration phase and move the sensors over both  
  // reflectance extremes they will encounter in your application: 

  int i;  
  for (i = 0; i < 250; i++)  // make the calibration take about 5 seconds  

void loop()  
  unsigned int sensors[3];  // change 3 to whatever number of sensors you are
                                     // using
                                     // get calibrated sensor values returned in the sensors
                                     // array, along with the line position  
                                     // position will range from 0 to 2000, with 1000 
                                     // corresponding to the line over the middle sensor  
  int position = qtr.readLine(sensors);  
// output to Serial monitor
Serial.print(" ");
Serial.print(" ");
Serial.print(" ");
Serial.println();    // add cr/lf to serial display

  // if all 3 sensors see very low reflectance, take some appropriate action for
  // this situation
  if (sensors[0] > 750 && sensors[1] > 750 && sensors[2] > 750)
   digitalWrite(ledPin, HIGH);
   digitalWrite(ledPin, LOW); 
  // compute our "error" from the line position.  We will make it so that the
  // error is zero when the middle sensor is over the line, because this is our
  // goal.  Error will range from -1000 to +1000.  If we have sensor 0 on the left
  // and sensor 2 on the right,  a reading of -1000 means that we see the line on
  // the left and a reading of +1000 means we see the line on the right.  
  int error = position - 1000;  
  int leftMotorSpeed = 100;  
  int rightMotorSpeed = 100;  
  if (error < -500)  // the line is on the left  
    leftMotorSpeed = 0;  // turn left  
  if (error > 500)  // the line is on the right  
    rightMotorSpeed = 0;  // turn right  
  // set motor speeds using the two motor speed variables above  

Thanks for any help!



Can you start by simplifying this code as much as possible, including removing the calibration section, using instead of qtr.readLine(), trying just a single sensor, and explaining precisely what all of your connections are? You should also tell us what board you are loading that code onto. That will make it easier for us to figure out what you are doing wrong or to reproduce the problem over here.