I cannot build houses or anything, help?

I cannot build houses or anything, help?

I recently bought Sims2 nightlife.
I installed it, etc.

Well, when ever i start to build a new house from scratch, the land is always really hilly and bumpy, and when i build walls, it won't let me build 2nd stories and put flooring down because there is bumpy patches inside my house.
How do i change this..or is there anything I can do>

 

You might want to try flattening the land on the lot using the terrain tool in Build Mode. For future housebuilding you may try to find a space of land that's not so bumpy.

 

There's also the foundation tool.

 

I had this problem too. But instead of using that land i just ought a land that was flat