Why every time I use an Union there is a problem with the collisions?

[NACER_RPG (NACER)]

Hello I made a wall and wanted to add a door to it using the “negative parts”
so what I did:
I took a part I resized it to make it the shape of the door then I made it negative part I made an union between the wall and the negative part after all this I got the wall with the hole in it but when I runned the game and tryed to pass through the hole his collisions were messed up I’ll explain, a part of the hole had collisions and the other part had no collisions but I want the hole to have no collisions because the player is supposed to pass through the hole.

Can someone tell me what to do?

[Scottifly]

Check out this link: CollisionFidelity | Roblox Creator Documentation. You also need to realize that if you Negate a very small area from a large Union it won’t necessarily create a physical shape that’s the same as the visible Union.
If you Negate a section from the edge rather than the middle of a Union it might work out better.