cant find problem

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C#

ASP.NET

List<string> myControlList;
CheckBoxList SubCategoryChkboxLst = new CheckBoxList();

the above two are declared as global in load.
this is for saving in to viewstate:

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);
  }
}

CategoryChkboxLst

is the above "CategoryChkboxLst" control I drag droped into my page on selected change event of categoryChlboxlst I am trying to generate dynamic checkbox list which is undertcategory.

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.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 am not able to find errors
1) same control with same name. I cleared everying but still it coming.
2) one selected change event generating one checkboxlist on another selected change event it generating but first one is getting clear.