Adjustment of Contrast in C#, differences netdc8 / picocom2

Hello

here is a VS2008 CF35 sample how to adjust contrast under Windows CE, in C# written.
The sample has a trackbar to change current contrast value, the button is used to store it permanent in registry. Registry value is loaded to the trackbar after init.

I tested it with Netdcu8 and it works. Values are changing expected and are stored permanent in registry and are used after device power off.

But for Picomod2 I got different behavoiur, sometimes the display goes black when trackbar is used and the reslution (should be 0..4095) is also not the same. Nearly only 3 values are to see: bright , a bit less bright and black display.
When i look in the registry after a picocom2 trackbar change(whithout pressing the button), the value is not the value from the trackbar(0..4095) but something undefined. Lets´s say I change trackbar from 0 to 200, the value in the registry is may be 24 or whatever but not 200.

I use a Hitachi TX09 320x240 LCD.
Can anybody see any errors here in coding or thinking?
I need one and the same software to running on both devices netdc8 and picocom2.

bye
Andreas

Hello

Yes now it is clear. I got it working, but netdcu8 has range up 4095 not ox3ff!
This is the neccesary additional code for c# if anybody needs it:

bye
Andreas