My temperature sensor provided by Maxim was actually DS18B20 instead of DS18S20. I found this by carefully observing the sensor's surface with a magnifying glass. I never had doubts about this. The resemblance between "B" and "S" made me spend many hours of frustrating time. Sorry for the viewers.

Shozo Kanamori
It's not easy for hobbyists to get DS18S20 here in Tokyo.