I tested a QRD1114 reflective sensor using a voltage meter, and was working great. I was getting good responses from the sensor (one of the sensors I was using had a bad LED which was not working, but the sensor worked fine with an external IR LED that I had laying around.) But as soon as I hooked it up to an analog input pin of my arduino board, and used the serial communications to display the reading from the sensor on the serial monitor, every reading would be 1023 (which should be the highest possible reading) even when there wasn't anything near the sensor. I changed the pin, so I know it isn't a defective pin. I repeated the test with a photo cell and got similar results. what could be the problem, and what can I do about it?