Sorry i was wrong, i want to write on the italian forum.
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html . Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Can you post a link to data/specs of your sensor please?
Some are just switches and you cannot adjust sensitivity.
What model Arduino are you using?
Thanks.. Tom... 