Constructor on type 'css_root+Script' not found.

[MetSystem]

version: 1.3.1 dotnet: net core 3.1

CSScript.RoslynEvaluator
//                    .LoadCode(@"using System;
//public class Script
//{
//    public int Sum(int a, int b)
//    {
//        Console.WriteLine(a+b);
//        return a+b;
//    }
//}");
 .LoadFile("SumScript.cs", string.Empty);  

SumScript.cs：

using System;
public class Script
{
    public int Sum(int a, int b)
    {
        Console.WriteLine(a+b);
        return a+b;
    }
}

result: success: LoadCode fail: LoadFile

[MetSystem]

.LoadFile("SumScript.cs", null);