Getting enums from imported .net core dll in powershell

I’m trying to load enums from a .netcore dll that I imported in powershell. I tried many actions:

Add-Type -Path dllpath

and then called: [MyEnum]::enumName

I got this Exception :

Could not load file or assembly 'System.Runtime, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system 
cannot find the file specified.

Can you please let me know if I’m missing anything. How to get these enums ?