EDSDK Press Shutter Button remotely

I'm trying to remote control my Canon EOS 1000D with Canon's EDSDK 3.6.1 in C#.

I'm calling

uint CameraCommand_PressShutterButton  = 0x00000004;
uint CameraCommand_ShutterButton_Completely = 0x00000003;

int error = EdsSendCommand(camRef, CameraCommand_PressShutterButton, CameraCommand_ShutterButton_Completely);

However, EdsSendCommand always returns 0x00000060 what means "invalid parameter".

Any ideas, what went wrong here? 3 is the parameter I found on this tutorial. I tried CameraCommand_ShutterButton_Completely_NonAF = 0x00010003 as well with the same result.

Or is there another way to remote shutter this camera?

The 1000D is quite old already and it is most likely that it does not support the shutter button command. This command is (to my knowledge) the only one (besides video) that is only supported by newer cameras.

If you just want to take a picture, you can use the TakePicture command (ID is 0, parameter also 0).