Problem when select data to datagridview with where

the select statement is not running 

public partial class FM_Mini_Products : Form
{
    SqlConnection sqlcon = new SqlConnection(@"Server=ADMIN-PC\SQLEXPRESS;Database=ELMANAR; Integrated Security = True");
    SqlDataAdapter da;
        
    DataTable dt1 = new DataTable();
       
    Presintaion_Layer.FM_TBL_Invoice inv = new FM_TBL_Invoice();
    Data_Access_Layer.DataAccessLayer DAL = new Data_Access_Layer.DataAccessLayer();
      
    SqlCommand cmd = new SqlCommand();

    public FM_Mini_Products()
    {
        InitializeComponent();

        da = new SqlDataAdapter("SELECT pr.id_product as 'NO',pr.name_product as 'Name',pr.sale as 'SAle',pr.Qty as 'Qty',s.store_name as 'Store' from TBL_Products  pr inner join TBL_Store as s on s.fk_id = pr.fk_idStore         where s.store_name like '%" + inv.comboStore.Text + "%'" , sqlcon);

            da.Fill(dt1);
            dataGridView1.DataSource = dt1;
          
    }