My table is not updating

Hi

Please try this code

string connString = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;

            SqlConnection conn = new SqlConnection(connString);


            string updateCommand = "update  [Users] set FirstNameLastName=@FirstNameLastname," +
                                   " Gender=@Gender," +
                                   " PlaceOfBirth=@PlaceOfBirth," +
                                   " DateOfBirth=@DateOfBirth," +
                                   " EducationLevel=@EducationLevel," +
                                   " EducationInstitution=@EducationInstitution," +
                                   " Employer=@Employer, " +
                                   " Position=@Position " +
                                   " where UserName=@UserName";
            

            SqlCommand cmd = new SqlCommand(updateCommand, conn);

            cmd.Parameters.AddWithValue("@FirstNameLastName", txtImePrezime.Text);
            cmd.Parameters.AddWithValue("@Gender", rblPol.SelectedValue);//radio button
            cmd.Parameters.AddWithValue("@PlaceOfBirth", txtMesto.Text);
            cmd.Parameters.AddWithValue("@DateOfBirth", Convert.ToDateTime(txtDatum.Text));
            cmd.Parameters.AddWithValue("@EducationLevel", txtObrazovanie.Text);
            cmd.Parameters.AddWithValue("@EducationInstitution", txtInstitucija.Text);
            cmd.Parameters.AddWithValue("@Employer", txtVrabotenVo.Text);
            cmd.Parameters.AddWithValue("@Position", txtPozicija.Text);
            cmd.Parameters.AddWithValue("@UserName", User.Identity.Name);

            conn.Open();

            cmd.ExecuteNonQuery();//error line
            conn.Close();