Dynamically adding Page size dropdown list in the Gridview Pager

I have a Gridview for which Dropdown list has to be added on the run time at the Pager row. I have added the below code on the Gridview RowCreated.

protected void gv_transaction_RowCreated(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.Pager)
    {
        using (DropDownList ddlpagesize = new DropDownList())
        {
            ddlpagesize.Items.Add("25");
            ddlpagesize.Items.Add("50");
            ddlpagesize.开发者_运维知识库Items.Add("75");
            ddlpagesize.Items.Add("100");
            ddlpagesize.Items.Add("150");
            ddlpagesize.Items.Add("200");
            ddlpagesize.AutoPostBack = true;
            ddlpagesize.Items.FindByText(gv_transaction.PageSize.ToString()).Selected = true;
            ddlpagesize.SelectedIndexChanged += ddlpagesize_SelectedIndexChanged;
            using (Table tbl = (Table)e.Row.Cells[0].Controls[0])
            {
                using (TableCell cell = new TableCell())
                {
                    cell.Controls.Add(new LiteralControl("<b>Page Size: </b>"));
                    cell.Controls.Add(ddlpagesize);
                    tbl.Rows[0].Cells.AddAt(0, cell);
                }
            }
        }
    }
}
protected void ddlpagesize_SelectedIndexChanged(object sender, EventArgs e)
{
    using (DropDownList ddlpagesize = (DropDownList)sender)
    {
        gv_transaction.PageSize = int.Parse(ddlpagesize.SelectedValue);
        gv_transaction.PageIndex = 0;
        BindTransactionGrid();
    }
}

Now, SelectedIndex change event is not firing, when I change the dropdownlist value. But interestingly, when I remove the using statement from the initiation of page size Dropdownlist; Selectedindex event is firing perfectly. Please tell me if there is any relation with the disposing of dropdownlist and selectedIndex Changed event for the dynamic dropdown in a Gridview

You don't need to wrap asp.net controls in using statements, asp.net will call dispose automatically on your controls, i think your using statements are causing them to be disposed too early.