   int error = -1; // Set to first laser we can't calibrate.
   for (int i = 0; i < inputCount; ++i) {
     thresholds[i] = (minLasersOn[i] + maxLasersOff[i]) / 2;
-    Serial.print(i);
+    Serial.print(i+1);
     Serial.print(": ");
     Serial.print(thresholds[i]);
     
     if (minLasersOn[i] - maxLasersOff[i] < minCalibrationGap) {
+      thresholds[i] = -1;
       Serial.print("  CALIBRATION FAILED!");
       if (error == -1)
         error = i;

        // If different than last value, send notification.
        if (newInput != current[i]) {
            if (newInput)
              Serial.print('a' + i); // HIGH means laser detected -> interruption OFF
            else
              Serial.print('A' + i); // LOW means laser not detected -> interruption ON
         }
        current[i] = newInput;
    }  

void displayCalibrationData()
{
  for (int i = 0; i < inputCount; ++i) {
    Serial.print(i+1);
    Serial.print(": ");
    Serial.print(calibrateMin[i]);
    Serial.print(" to ");
