สอบถามเรื่องการ insert ข้อมูล 2 ตารางครับ เกิดปัญหา insert แค่บางส่วนครับ

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Configuration;
using System.Web.Configuration;
using System.Data.SqlClient;
using System.Security;
using System.Text.RegularExpressions;
using System.IO;


namespace ClassRoomManagementSystem
{
    public partial class manual : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (Session["LOGIN"] == null)
            {
                Response.Redirect("login.aspx");
            }
            else
            {
                lblLOGIN.Text = Session["LOGIN"].ToString();
                if (Convert.ToInt32(Session["ACCESS"]) == 01)
                {
                    pnADMIN.Visible = true;
                    pnUSER.Visible = false;

                }
                else
                {
                    pnADMIN.Visible = false;
                    pnUSER.Visible = true;

                }
            }
            PopulateYearList();
        }
        protected void PopulateYearList()
        {
            ddlyear.Items.Clear();
            int year;
            for (year = DateTime.Now.Year; year <= DateTime.Now.Year + 5; year++)
            {
                ddlyear.Items.Add(System.Convert.ToString(year + 543));
            }
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            String url = null;

            string strConnString, strSQL;
            string condition = "9";

            SqlConnection objConn = new SqlConnection();
            SqlCommand objCmd = new SqlCommand();

            SqlConnection myconn = new SqlConnection("Server=WPEE-PC\\SA;   
            UID=sa;PASSWORD=1q2w3e4r;DATABASE=dbCRMS;MAX Pool Size=400; Connect Timeout=600;");
            String username;
            String sqlStr = "select top 1 COURSE_ID from tblCOURSE order by COURSE_ID DESC";


            SqlCommand myCmd = new SqlCommand(sqlStr, myconn);
            myconn.Open();

            object maxID = myCmd.ExecuteScalar();

            myconn.Close();

            username = maxID.ToString();

            strConnString = "Server=WPEE-PC\\SA; UID=sa;PASSWORD=1q2w3e4r;DATABASE=dbCRMS;MAX Pool Size=400; Connect Timeout=600;";
            strSQL = "Insert Into tblCOURSE (COURSE_CODE,COURSE_NAME,TEACHER,CREDIT,LEC,QUANTITY,COURSE_YEAR,COURSE_TERM,CONDITION) " +
                       " values ('" + txtcourse_code.Text + "','" + txtcourse_name.Text + "','" + txtteacher.Text + "','" + txtcredit.Text + "','" + txtlec.Text + "','" + txtquantity.Text + "','" + ddlyear.Text + "','" + ddlterm.Text + "','" + condition + "')";

            strSQL = "Insert Into tblRESERV_ROOM (RESERV_ROOM,RESERV_DAY,USER_NAME) " +
                     " values ('" + ddlROOM_NAME.Text + "','" + DropDownList1.Text + "','" + username + "')";

            objConn.ConnectionString = strConnString;
            objConn.Open();
            objCmd.Connection = objConn;
            objCmd.CommandText = strSQL;
            objCmd.CommandType = CommandType.Text;

            objCmd.ExecuteNonQuery();
            objConn.Close();
            objConn = null;

            url = "reserv-management.aspx";

            Response.Redirect(url);
        }
    }
}