(Un)fortunately the whole thread does not have enough words to describe your hardware setup or sketch in required detail to find such difficult problem. You see that I allready asked such trivialties as "is gnd connected".
I have a handfull of likewise questions at ready but don't really like to compensate missing info with upping my workload (by typing) when everything could be solved by a simple copy&paste from your side.
Then everyone has all necessary info at hand to ponder the symptoms, set up the scenario and try to hunt down the problem.