Hey,guys.Any body can help me with this problem about steam VR?

I have tried many times and searched for many pages and information about this problem,Which is that the Steam VR can not detect any UE4 VR projects ,even VR template.
Anybody can help me?

And my last question was that the VR preview mode button is grey,I had solved this by myself.
You just need to go into your plugins,and enable or disable one of other VR plugins, such as Google VR,Gear VR,etc.
And restart the project ,the problem will be solved.

Maybe it is a problem of versions,I found any kinds of versions higher than 4.15 are not avaliable,and when you first create a project ,the vr preview button is grey,Which means that this kind of version are not useful for Steam VR?