Minecraft Decocraft not working why?

I downloaded mods in Minecraft. And I started Minecraft, I took furniture that I wanted to place and tried to place it, but it doesn't work, why is it? I use forge and the normal minecraft launcher then got all forge mods in the mod folder everything is in Minecraft but I can't place furniture. Could you possibly help to find the error lg

Do you play single player? If the server doesn't have the mods, that won't work. It should normally work in single player.

I play single player but it doesn't work

What could it be?

It could be that the mod is blocked by another.