SourceGenerator Didn't Work Appropriate?

I followed this guide(Unity - Manual: Roslyn analyzers and source generators) to learn how it works, things goes well at first, but when I restart Unity, it says

, a typically error suggests that there is not such a class. So I need to replace the .dll file out and back to the Plugins folder to make SourceGenerator work again, and seems I need to do it every time. Is this a normal circumstance? By the way I got a warning when it work:

Not sure what I did was wrong, and it’s too hard for me to search for an answer:(, this is a new tech after all.

I found the answer, I forgot to set Asset Labels. Silly me!8418828--1113648--Pic.jpg