When using a daylight sensor to power a sticky piston; in this case to lift a redstone block, to power a light source at night.

Symptoms: Normally, at night, uncovered, the piston is retracted and the lights come on. During the day, piston is powered, pushes the piston down and breaks the circuit.

Affected behaviour: (note blocks not touching the sensor - this occurs with at few blocks of air above the sensor) enveloped in glass block, and then covered with one layer of water, the daylight sensor sends a signal during the day to power the piston, but reverses at night; effectively opposite behaviour.

When covered by double glass block followed by single layer of water, the daylight sensor becomes inoperative during day and night.

When covered with transparent blocks directly next to and above the daylight sensor, and covered by water, sensor becomes inoperative during day and night.