Capacitve touch stability

Hi, I am using this library :
http://playground.arduino.cc//Main/CapacitiveSensor?from=Main.CapSense
to control 4 touch keys beneath a plastic panel to drive some servos.
I ran through some noise issues which I solved with grounding the arduino and adding some capacitors as suggested in the article.

But still it is not very reliable for something permanent! Sometimes the servos are turned on without anyone in the room!
I tried using different sampling rates and different methods from the library but still it is not very stable!

So what do you recommend for a stable capacitive-sensing chip that is easy to implement with arduino?

Probably - an Arduino.

The Arduino is the least likely to be a critical part of your setup.

My suspicion would be - your plastic panel. Acrylic ("Perspex")? Is its surround grounded as well as the Arduino? What is the environment? Air conditioning?

As always, the actual circuit you are employing and a photograph of your setup would be useful if we were to look for clues.

Paul__B:
Probably - an Arduino.

The Arduino is the least likely to be a critical part of your setup.

My suspicion would be - your plastic panel. Acrylic ("Perspex")? Is its surround grounded as well as the Arduino? What is the environment? Air conditioning?

As always, the actual circuit you are employing and a photograph of your setup would be useful if we were to look for clues.

Sorry for the late reply but we got hit by a severe snow storm and had to stop working on my projects.
Here is the circuit:

The red wires go to the foil and the yellow ones control two servos.
Digital Pin 9 is the "send pin" and Pins 4 through 8 are "Receive pins"
I used 10M resistors and tried using 120pF and 22pF and 330pF capacitors , I didn't notice much difference in the performance.
also tried removing all capacitors the system went unstable then and sensitivity dropped horribly!

The Arduino is inside a water cooler. The cooler is earthed and so is the Arduino.
I am not sure what kind of plastic the panel is but it a 3 mm thick.
a photo of the setup :

There seems to be water in your equipment!

This is not going to go very well with touch sensors, which rely on almost perfect insulation of all parts.

Your circuit is not accurate either, but the photos imply the actual configuration.

The problem is presumably condensation on any or all of the connections on the Pro Mini and to the foils. Even pure water condensation may form drops which will alter capacitance.

You need the Arduino itself to be placed immediately adjacent to the touch plates with no long wires, and you need a totally effective moisture barrier between this and the tank, which in this case might be a plastic sheet glued effectively airtight over the whole top section. You need to ensure that top section including the Arduino is totally dry before sealing it up (each time you alter it). If operating properly, you should not need the capacitors at all unless perhaps some other nearby appliance (such as a motor) is generating substantial electrical interference.

In my previous job, electronics assembly, we used to cast loads boards/parts in resin to get them waterproof and you could make a waterproof sensor by simply using a piece of PCB with a few layers of paint.

I'd be sure everything works in a dry environment first though, making adjustments later is like unscrambling eggs.