Passing .NET objects via COM interop using Delphi and the JCL .NET code

I am basically trying to do:

Passing strongly typed arguments in .NET COM interop

But using Delphi and JCL to do it. I am admittedly NOT a COM guru and have done searches but can't quite find an answer to what I am trying to do. I have C# with this:

using System.Runtime.InteropServices;

namespace Example1ClassLibrary
{
    [ComVisible(true)]
    public class Example1
    {
        public Example1Obj AddByObj(Example1Obj Obj)
        {
            var ret = new Example1Obj();
            ret.XVal = AddFunction(Obj.XVal, Obj.YVal);
            ret.YVal = 0;
            return ret;
        }
    }

    [ComVisible(true)]
    public class Example1Obj
    {
        public int XVal;
        public int YVal;
    }
}

And Delphi:

procedure TfrmMain.FormCreate(Sender: TObject);
begin
  Host := TJclClrHost.Create('v4.0.30319');
  Host.Start();
  Obj := Host.DefaultAppDomain.CreateInstance('Example1ClassLibrary', 'Example1ClassLibrary.Example1').UnWrap();
end;

procedure TfrmMain.Button4Click(Sender: TObject);
var
  Pass: OleVariant;
  Ret: OleVariant;
begin
  Pass := Host.DefaultAppDomain.CreateInstance('Example1ClassLibrary', 'Example1ClassLibrary.Example1Obj').UnWrap();
  Pass.XVal := StrToInt(EditX.text);
  Pass.YVal := StrtoInt(EditY.text);
  Ret := Obj.AddByObj(Pass);
  EditResult.Text := Ret.XVal;
end;

When I click Button4, I get the

EOleSysError "The parameter is incorrect".

at the line:

Ret := Obj.AddByObj(Pass);

Is what I'm trying to do possible, and if so, what am I missing. Note: Simple types works fine so actually loading the assembly, creating the object, and calling a method with simple types works great.