c# import Excel Files - error references

Question

Hello 

I have a small problem. I want to import Excel files using C# but when i declare a variable like this xlsApp = new Excel.ApplicationClass() I receive this error : The type or namespace name 'ApplicationClass' does not exist in the namespace 'Excel' (are you missing an assembly reference?. 

I added the following references : Microsoft Excel 12.0 Object Library, Microsoft Excel 5.0 Object Library and Microsoft.Office.Interlop.Excel and it stil dosen`t work. 

This is my code

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using Excel;

using System.Linq;

using System.Text;

using System.Windows.Forms;

namespace PC_Management3

{

    public partial class BrowseExcel : Form

    {

        public BrowseExcel()

        {

            InitializeComponent();

        }

       

        private void button1_Click(object sender, EventArgs e)

        {

            //open file

            OpenFileDialog fdlg = new OpenFileDialog();

            fdlg.InitialDirectory = @"d:\";

            fdlg.Filter = "All files (*.xls)|*.xls|All files (*.*)|*.*";

            fdlg.FilterIndex = 2;

            fdlg.RestoreDirectory = true;

            if (fdlg.ShowDialog() == DialogResult.OK)

            {

                textBox1.Text = fdlg.FileName;

            }

            //excel stuff

            Excel.Application xlsApp;

            Excel.Workbook xlsWorkbook;

            Excel.Worksheets xlsWorksheet;

            xlsApp = new Excel.ApplicationClass();

        }

        

    }

}