dynamic checkboxlist created getting clear in any event like dropdown Selected change

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C#

ASP.NET

Sir am Generating Dynamic Checkboxlist on selected change even of main Checkboxlist.
the below code........

protected void CategoryChkboxLst_SelectedIndexChanged(object sender, EventArgs e)
       {

           for (int i = 0; i < CategoryChkboxLst.Items.Count; i++)
           {
               if (CategoryChkboxLst.Items[i].Selected == true)
               {
                    objdc.ItemID = Convert.ToInt32(CategoryChkboxLst.Items[i].Value);
                    SubCategoryChkboxLst = new CheckBoxList();
                    SubCategoryChkboxLst.ID = "SubCategoryChkboxLst_" + objdc.ItemID;
                   if (SubCategoryPnl.FindControl(SubCategoryChkboxLst.ID)!=null)
                   {
                       this.ViewState.Remove(SubCategoryChkboxLst.ID);
                    SubCategoryPnl.Controls.Remove(SubCategoryPnl.FindControl(SubCategoryChkboxLst.ID));
                    myControlList.Remove(SubCategoryChkboxLst.ID);

                   }

                   DataTable dt = new DataTable();
                   dt = objbl.GetSubCategories(ref objdc);
                   
                   SubCategoryChkboxLst.DataSource = dt;
                   SubCategoryChkboxLst.ID = "SubCategoryChkboxLst_" + objdc.ItemID;
                   SubCategoryChkboxLst.DataTextField = "SUB_ITEM_NAME";
                   SubCategoryChkboxLst.DataValueField = "SUB_ITEM_ID";
                   SubCategoryChkboxLst.DataBind();
                   SubCategoryChkboxLst.RepeatColumns = 5;
                   SubCategoryChkboxLst.RepeatDirection = RepeatDirection.Horizontal;
                   //lblYear.ID = "lbl_" + li.Value;

                   SubCategoryPnl.Controls.Add(SubCategoryChkboxLst);
                   SubCategoryPnl.Controls.Add(new LiteralControl("<br>"));
                   myControlList.Add(SubCategoryChkboxLst.ID);
                   ViewState["myControlList"] = myControlList;



               }
           }

       }

i added to view state to save controls

protected override void LoadViewState(object savedState)
{
    base.LoadViewState(savedState);
    myControlList = (List<string>)ViewState["myControlList"];
    foreach (string ctlID in myControlList)
    {

        CheckBoxList cklt = new CheckBoxList();
        cklt.ID = ctlID;
        LiteralControl lineBreak = new LiteralControl("<br />");
        SubCategoryPnl.Controls.Add(cklt);
        SubCategoryPnl.Controls.Add(lineBreak);
    }


}

but on any dropdown change event or button click event generated list box is getting clear .wht is the proble please can any one help.

and i how how can i get control id in Save button