Why is this not a house?

Hello my fellow Pokélandlords, pokémayors and pokéresort managers, I was trying to build a custom house for one of my beloveds, but I realized that after setting up the walls and the door I still didn't get the shiny sparkles informing that it is in fact a house. Can someone help me figure out what I'm doing wrong?

https://preview.redd.it/x2ui0eqmd7og1.png?width=1920&format=png&auto=webp&s=ae57fc035d2a98a910f83066aa1c07a78c8811db

The spheals are covering potential spoilers, the building in question is the rectangular one with blue flooring.

Thanks in advance.