Calling matlab function from VisualStudio C#

Hi everybody, I need your help!!

MATLAB FUNCTION (R2018a)

function Result = FunSum(a,b)
Result = a+b;
end

My code in Visual Studio 2017, in a Windows Form project is:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SumApp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnSum_Click(object sender, EventArgs e)
        {
            double A = Convert.ToDouble(txtA.Text);
            double B = Convert.ToDouble(txtB.Text);
            
            MLApp.MLApp matlab = new MLApp.MLApp();
            matlab.Execute(@"cd c:\FunSum");
            object result = null;
            matlab.Feval("FunSum", 1, out result, A, B);
            object[] res = result as object[];
           
            txtR.Text = Convert.ToString(res[0]);
        }
    }
}

..now, friends, the error that i see is:

System.Runtime.InteropServices.COMException: 'Undefined function 'FunSum' for input arguments of type 'double'.'

but, this is not true, because the code sometimes has worked!!! anyone of you could help me?

thanks

[Nguyen]

Hello,

Does your code work now?

I have the same error.