Subtractive Brush type not working?

I’m trying to make a doorway. I have copied the previous wall. Re-sized it to a suitable door size. I changed the type to subtractive. When trying to move it into my wall, it doesn’t remove that piece of the wall. Any insight would be appreciated. I am using BSP’s by the way.

Off the top of my head, are the brushes in the correct order?

Order does matter when using BSP brushes, more about that can be found in the documentation:

Yes!! You can copy and paste the substracted shape so it can go after the additive in the World Outliner Panel. Delete the first one :smiley: