Wawa:
Yep.
(1200k * 100k) / (1200k + 100k) = 92.3k impedance.Try adding a 100n cap from analogue pin to ground.
That will give the A/D a 'solid' voltage to sample from.
Leo..
Even with the cap it will present some trouble. Do diminish the impedance below 10 kOhm.
Regards.