ACorn12

I created a new document and went to Terrain -> Create Terrain Perimeter. It draws a terrain of 15x30m by default. For testing, I kept this size. I added elevation lines like show in this picture: As you can see I set elevation at 0mm at the bottom. Then two elevation lines of 400mm (where the house sits). And as a test two elevation lines of -400mm for the backyard. I expected it to draw a terrain like described above but instead got something totally different. This is what I get:

Ok. So I'm using Home Designer PRO 2021. (I'm new. Just started using/experimenting today). The terrain I want to draw looks like the attached picture. Left is the street level (0cm). It goes up to where the house is. At the back of the house it goes to a level lower than the street. The terrain is flat where the house stands. And the backyard is flat too. Just these two curves I can't get it done

Our terrain is rectangular but not flat. At the front, on the street side, we call this level 0 at height 0cm Where the house stands it's a flat terrain that's a bit higher then the street. About 40cm higher. So from the street side it goes up to the front door, about 40cm higher than the street. At the back, about 4 meters from the back of the house, the terrain starts to lower. About 8 meters from the back of the house (level is about -80cm there) is the lowest point and it's flat all the way to the end of the terrain from there. So I added these elevation lines: At the front of the terrain: elevation 0mm (0cm) At the front door: elevation: 400mm (40cm) At the back of the house: 400mm (40cm) 4m from the back of the house: 400mm (40cm) 8m from the back of the house: -80mm (-80cm) At the back of the terrain: -80mm (-80cm). But that clearly doesn't do the job so I'm probably not understanding it correctly. Can anyone help me understand how to draw this terrain in home designer? Thanks!