Dear Onur,
If you draw two several roof frames one after another with the same plan the command “click edges of the roof frame to apply slopes” won’t work. You have to delete the roof frame and draw it again.

You’ll get 2 roof ridges and a “flat roof” if the upper edge (Z-coordinate) was chosen too small. The roof frame will be capped in that height. Otherwise the roof slopes connect at the highest point. (see pic)

best regards
Undine