'Focus' and 'HUX' doesnt exist

I started a project from MR Design Lab which is interacting objects. but there are certain errors which are i am facing.
**The type or namespace name Focus' does not exist in the namespace HUX'. Are you missing an assembly reference?
**
**The type or namespace name InteractionSourcePressType' could not be found. Are you missing an assembly reference?** **The type or namespace name InteractionSourceUpdatedEventArgs' could not be found. Are you missing an assembly reference?
**

Previously on the same settings i worked on different applications and it worked perfectly i dont know whats the problem

Script association is also getting lost again n again. Is that a bug in Unity ?
any ideas ?

@neerajwadhwa

Thanks in Advance