Insert Windows on walls

[Lumaja]

Import a window Modified the sizes and drag to the top of 90cm high horizontal Wall, when the drag touches the wall it turns vertical and not possible to insert.
With different window the action is different, dragging to the wall I can insert inside or outside but not on a wall, I had no problem with doors.
Can please some one explain what I am doing wrong.
Thank you

[hansmex]

When you import a door or window, you have to put a check mark in the box where it says Door/Window.
This basic stuff is covered in the User's Guide ....