Roller coaster not stackable

Spycoo16​  Please try a different lot, and of course flatten it and place the wood flooring to keep it flat as the video describes.  It's possible the lot you've been using is broken somehow.

If that doesn't help, let me know what kind of install this is: EA App, Steam, or disc.

Ok I click flatten lot, then add wood but even on the surfaces without wood the one story pieces still have the squares on top to stack and the two and three story pieces dont. But yes I have tried it all. I play in riverview and  twinbrook, so theyre not custom worlds, theyre official worlds. 

I play through discs I got on ebay and I bought it on EA store. Its a sims3pack file thats saved into my game launcher.

5pm edit: I also used the delphy culver sims3pack cleaner and none of the files were red.

7pm Second Edit: Ok I found a small 20/30 lot in riverview, flattened the lot and did NOT put any tiles, and all levels are stackable now.

The up/down piece still sticks in the floor but it can attach. Is that ok? 

Also, is it a lot issue? I feel like when I click "flatten lot" its not flattening enough? Because I went to a 64x64 lot in sunset valley, and got the same problem again, where theres no squares on top.

Sorry for all the messages but I also can only stack once. In the vid it says you should be able to go up to 5 stories, but  I cant. And whatever piece I stack on top, does not have the squares for stacking. 

9pm Edit: Ok another update, I elevated then flattened, then put floor on the 64x64 sunset valley lot and was able to functionally stack and use all pieces. I am pretty lost on why. I do believe u when u say the lot must be flat, im more stumped on why the lot isnt flattening on regular elevation, and why floor doesnt help stabilize things!

Spycoo16​  It is possible that the lots you've been testing with are a problem.  I'm happy to look them over in my game; just list the addresses.  For the wood flooring, it's critical that you start at one corner and cover the entire lot in one go.  If that doesn't work, undo the covering, then try starting from a different corner.

It's clear at least that the items are working in your game, so there must be something about the terrain or the lot in general that's interfering.  I wouldn't think spawners would cause issues all over the lot, but just in case there's something invisible, it's always good to build a bit on a lot (a couple of walls is enough), then bulldoze in Edit Town before starting your actual build.  That gets rid of most hidden items.

Riverview:

• 451 Riverview Road: Didnt work for just flat lot; flattened lot with wood floor worked for one story only; when I elevated the terrain then flattened and put wood on the elevated floor, all levels worked
• 345 Riverblossom Hills Drive: Didnt work for flat no wood; flattened lot with wood works for one story pieces only; when I elevated the terrain then flattened and put wood on the elevated floor, all levels worked
• 750 Old Farm Road: Didn't work on flateed lot, lot with wood or when I elevated the terrain then flattened and put wood on the elevated floor. Nothing worked
• 35 Hidden Grove Lane: Didnt work on flat lot; flattened lot with wood floor worked for one story only; when I elevated the terrain then flattened and put wood on the elevated floor, all levels worked
  
  

Twinbrook:

• 16 Puddlewick Drive: Didnt work for just flat lot; flattened lot with wood floor worked for all levels
• 17 Sweetwater Loop: Didnt work for just flat lot; flattened lot with wood floor worked for one and two story pieces but not three stories; didnt try when to elevate the terrain and flatten and put wood on the elevated floor

I'm also curious if residential/community lot matters?

Ok im going to go try the secnd tip and see.