c# and ms access database problem asap

Question

i want to save data by save button from :

idbox (textbox) - empbox (combobox) - jobbox (combobox) - unitbox (combobox) -

destbox (combobox) - detectivebox (combobox) - statebox (combobox) -

investdate (datepicker) - investresult  (textbox)

        into the table investinside same order :

id - emp - unit - job - dest - detective - state - investdate - investresult

      i tried this one and had no errors but nothing was saved in the table when i check ....

                 here's the code i tried

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;
using System.Data.OleDb;

namespace beta_2
{
    public partial class Dentry_main : Form
    {
        OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=beta2.mdb;");
        OleDbDataAdapter da;
        DataSet ds = new DataSet();
        OleDbCommand com = new OleDbCommand();
        string sql;

        public Dentry_main()
        {
            InitializeComponent();
        }

        private void Dentry_main_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'beta2DataSet.stateinside' table. You can move, or remove it, as needed.
            this.stateinsideTableAdapter.Fill(this.beta2DataSet.stateinside);
            // TODO: This line of code loads data into the 'beta2DataSet.detectivestbl' table. You can move, or remove it, as needed.
            this.detectivestblTableAdapter.Fill(this.beta2DataSet.detectivestbl);
            // TODO: This line of code loads data into the 'beta2DataSet.departments' table. You can move, or remove it, as needed.
            this.departmentsTableAdapter.Fill(this.beta2DataSet.departments);
            // TODO: This line of code loads data into the 'beta2DataSet.units' table. You can move, or remove it, as needed.
            this.unitsTableAdapter.Fill(this.beta2DataSet.units);
            // TODO: This line of code loads data into the 'beta2DataSet.employees' table. You can move, or remove it, as needed.
            this.employeesTableAdapter.Fill(this.beta2DataSet.employees);

        }

        private void button1_Click(object sender, EventArgs e)
        {
            conn.Open();
            com.Connection = conn;
            sql = "INSERT INTO investinside([id],[emp],[job],[unit],[dest],[detective],[state],[investdate],[investresult])VALUES(@id,@emp,@job,@unit,@dest,@detective,@state,@investdate,@investresult)";
            com.CommandText = sql;
            com.Parameters.Clear();
            com.Parameters.AddWithValue("@id", idbox.Text);
            com.Parameters.AddWithValue("@emp", empbox.Text);
            com.Parameters.AddWithValue("@job", jobbox.Text);
            com.Parameters.AddWithValue("@unit", unitbox.Text);
            com.Parameters.AddWithValue("@dest", destbox.Text);
            com.Parameters.AddWithValue("@detective", detectivebox.Text);
            com.Parameters.AddWithValue("@state", statebox.Text);
            com.Parameters.AddWithValue("@investdate", investdatebox.Text);
            com.Parameters.AddWithValue("@investresult", investresultbox.Text);
            com.ExecuteNonQuery();
            MessageBox.Show("success");
            conn.Close();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}