An unhandled exception of type 'System.Data.EvaluateException' occurred in System.Data.dll;Additional information: Cannot find column [NrFir]

I created two forms:

Form 1 contains:

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 Plan_de_lucru_1._0
{
    public partial class frPlanMain : Form
    {

        public SearchWindow frm2;

        public frPlanMain()
        {
            InitializeComponent();
        }

        private void frPlanMain_Load(object sender, EventArgs e)
        {

        }

    private void GoButton_Click(object sender, EventArgs e) {
        string constr = "Provider = MicroSoft.Jet.OLEDB.4.0; Data Source=" + locTBox.Text + ";Extended Properties =\"Excel 8.0; HDR=NO;\";";
        OleDbConnection con = new OleDbConnection(constr);
        OleDbDataAdapter sda = new OleDbDataAdapter("Select * From [" + shTBox.Text + "$]", con);
        DataTable dt = new DataTable();
        sda.Fill(dt);
        CleanupDataTable(dt); // call the cleanup here, before binding dgv to dt
        dGVPlan.DataSource = dt;
        new SearchWindow(this).Show();
    }

    private void CleanupDataTable(DataTable dt) {
        if(dt.Rows.Count == 0)
            return;
        var headerRow = dt.Rows[0];
        var columns = headerRow.ItemArray;
            for (int i = 0, l = columns.Length; i < l; i++)
                dt.Columns[i].Namespace = columns[i].ToString();
        dt.Rows.Remove(headerRow);
    }
}
}

And Form 2 :

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 Plan_de_lucru_1._0
{
    public partial class SearchWindow : Form
    {
        public frPlanMain refTofrPlanMain;

        public SearchWindow(frPlanMain f) //<<Edit made here
        {
            refTofrPlanMain = f;
            InitializeComponent();
        }

        private void SearchButtonW_Click(object sender, EventArgs e)
        {
            BindingSource bs = new BindingSource();
            bs.DataSource = refTofrPlanMain.dGVPlan.DataSource;
            bs.Filter = "NrFir like '%" + searchTBoxW.Text + "%'";
            refTofrPlanMain.dGVPlan.DataSource = bs;


        }
    }
    }

When i click on the search button I receive the following error

An unhandled exception of type 'System.Data.EvaluateException' occurred in System.Data.dll; Additional information: Cannot find column [NrFir].

I have created columns in the DataGridView that referances to F1-F22 from a .xls file. NrFir is the column that i want to search in.

How can i fix the error ???