Jan,

This is a known problem. There is an easy solution:
1 - Locate a hatch and give it the dimensions (only width and height) of your door.
2 - Insert the hatch in your wall using the mouse. It will adapt to the thickness of your wall and create an opening.
3 - Give your door the desired dimensions.
4 - Now slide the door in your hatch, using the arrow keys on your keyboard. This will prevent the door from adapting to the wall.

Hans