ช่วยดูโค้ดหน่อยได้มั้ยคะ ไม่ไหวจริงๆ insert checkbox ใน gridview ไม่ได้ค่ะ error com.ExecuteNonQuery(); ตลอดเลย TT^TT

        protected void btnSave_Click(object sender, EventArgs e)
        {
            foreach (GridViewRow row in GridView1.Rows)
            {
                CheckBox cb = (CheckBox)row.Cells[0].FindControl("chkSelect");
                int RowIndex = row.RowIndex;
                int EID = (int)GridView1.DataKeys[RowIndex].Value;

                if (cb.Checked == true)
                {
                    SqlConnection conn;
                    SqlCommand comm;
                    string con = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
                    conn = new SqlConnection(con);
                    conn.Open();
                    comm = new SqlCommand("INSERT INTO CoursesEmployees(couID, empID) VALUES(@couID, @empID)",conn);
                    comm.Parameters.AddWithValue("@couID", TextBox1.Text);
                    comm.Parameters.AddWithValue("@empID",EID);  
                    comm.ExecuteNonQuery();
                    conn.Close();
                   
                }
            }
            Response.Redirect("AddEmp.aspx");
        }