Accessing digital notepad, DeviceIoControl returns error 55

See more:

C++

hardware

debugging

Hi,

I have some C++ code, which gets control of a digital notepad. The pen of the notepad uses the mouse's driver by default. I want to separate the pen from the mouse.

Ok. Firstly, I have all the code already and it's working. My problem is it is in C++ and the logic is integrated with the UI. Having absolutely no prior C++ experience or exposure, I set about separating the logic from the UI, so that I can call DllImport from my C# application.

I have successfully managed to get control of the pen (separate from mouse move and click). Now there is a GetData method, which just has to get the positioning of the pen in relation to the notepad. When I call the DeviceIoControl method in there, the GetLastError() is always 55, ERROR_DEV_NOT_EXIST. Strangely enough though, is that if I call DeviceIoControl with the IOCTL code to get the driver version, it is successful?

How would I go about finding out what my problem is?
Any help would be appreciated,
Niels