So, here I am again, but I am sorry to say that I did not get it right.

I wanted to model something like this:



So, I selected a room as big as the house level and a smaller room like this:



But instead of getting the roof with a cut out hole like on page 57 of the roof dormer tutorial I get this:



I am doing something wrong. Please tell me what to do. Could be that I did miss a step or did not understand the tutorial right.