Question How to set a camera

Hi there!

I working on 2D game and have a Canvas for game UI, at first my canvas render mode is screen space overlay But I have to change to screen space camera instead for some new features,

But I can't set a Main Camera to a canvas at all, even I create a new camera for it, But still can't!

I tried many ways such as drag a main camera object to it, But cannot drop or click a circle icon to searching for a camera But it just show nothing,

So how to do next? I tried to Google and I found that some people said, if they changed Unity version it can work, or this is a Unity Bug?

Thanks!!!

 

Oh anyone?