The typical scheme is 5V -> 10K resistor -> analog pin -> phototransistor -> GND (a "common emitter" scheme). This sets the pin high when it's dark and low when it's bright. I can't say I fully understand the math but it just seems to work better at typical light levels.
With your current wiring a larger resistor should give you more of a sensor swing.
So this scheme is not ok? I don't understand how you mean that i should wire it.. Can you make a scheme please?
And you recommend bigger resistor value.. I will try that. Any starting point (1M, 10M?)
Can somebody recommend any other sensor, which works well for this purpose? Btw, what kind of sensors are in those automatic turning on/off light detectors?