Capacitive sensor

i made Capacitive sensor with range 40 cm but , when i touch foil , ( long total= cs_4_2.capacitiveSensor(1);[/color] ) total gets higher , then when i get rid of arduino total is reducing , but it becames more then , it was before i touch foil , anyone knows this problem ?

It might get better, if you put a grounded piece of foil below it.

thanks , i found another solution , by this - cs_4_2.reset_CS_AutoCal(); - method