How to use a physics asset on another project?

I have a car project file in UE4. In this project, the car is moving as i wanted. It has no problem. I also can open and edit files such as physics asset, skeleton etc.
Now i want to use my works in that car project, in another project. I copied all the files that are realated to the car game to the new project. Once i click on phsics asset, it appears

( Warning: Physics Asset has no default SkeletalMesh assigned! For now, a simple default skeletal mesh (SkeletalMesh /Engine/EngineMeshes/SkeletalCube.SkeletalCube) will be used. You should repair the DefaultSkeletalMesh using UnrealPhAT (Edit -> Change Default SkeletalMesh) before saving this asset. )

This method that i used may be wrong. If it is, would you please guide me how can i use a physics asset in other projects?

I have coppied all skeletal mesh,vehicle blueprint, physics asset, skeleton and vehicle animation to other project once again and this time, it is working… i am confused!
This issue is vital to us to combine all the works that is being developed by all project members in one place. It is solved for us.