How to create a room inside Cuboid ?

Dear Vuforia Community,

in the last weeks I´ve got a problem which won´t let me continue my project.

I have a cuboid which is saved in Vuforia database and loaded in unity (Multi-Target + AR Camera).

I´d like to make the cuboid work as a room, which allow me to place 3D objects inside. Currently I am not able to lay some room over the cuboid.

The result is, that the cuboid is always been seen and sometimes it hides other 3D objects. I´ve made some investigation and found something on the net.

Here is a perfect example on how to create a room, which is built inside the cube: https://www.androidcentral.com/site...es/2018/02/school_merge _6_.jpg?itok=ur4jIaTQ(244 kB) https://www.androidcentral.com/site...es/2018/02/school_merge _6_.jpg?itok=ur4jIaTQ

As you can see, the cuboid is not seen, because another layer is displayed over the cuboid.And here you can see a screenshot of my current project: https://prnt.sc/om22ouI am using Unity 2019.1.10f + Vuforia 8.3. When I try to create a box, it just create a wall where i can not look through.I hope someone can help me out. That would be great.

Thanks in advance and best regards

Sarkis