my function does not execute this code while in sql server it gives me a good result

private void btnCalc_Click(object sender, EventArgs e)
       {
           label3.Visible = true;
           label4.Visible = true;
           try
           {

               con.Open();
               SqlDataAdapter da = new SqlDataAdapter("select * from pppp where res='" + this.label4.Text+ "'", con);
               DataSet ds = new DataSet();
               da.Fill(ds, "cal");
               DataView vd = new DataView(ds.Tables["cal"]);
               label4.Text = vd[0]["calr"].ToString();
               con.Close();
           }
           catch (Exception p)
           {
               MessageBox.Show(p.Message);
           }

       }