GridView/DataList无数据时依然显示表头

GridView/DataList无数据时仍然显示表头
GridView操作：
private void fillgv()
    {
        string str_sql = "select sp_gl.sp_no,sp_gl.sp_mc,sp_gl.sp_gg,sp_gl.sp_dw,sp_gl.sp_jg1,sp_gl.sp_bzsl,sp_gl.sp_bzsl*sp_gl.sp_jg1 as as_xdj,collect.co_rq from sp_gl,collect where sp_gl.sp_no=collect.sp_no and  collect.cu_id=+" + Session["UserId"].ToString();
        DataTable dt = con.ExcuteSelect(str_sql);
        this.GridView1.DataSource = dt;
        this.GridView1.DataBind();

        if (dt.Rows.Count == 0)
        {
            dt.Rows.Add(dt.NewRow());
            GridView1.DataSource = dt;
            GridView1.DataBind();
            int columnCount = GridView1.Rows[0].Cells.Count;
            GridView1.Rows[0].Cells.Clear();
            GridView1.Rows[0].Cells.Add(new TableCell());
            GridView1.Rows[0].Cells[0].ColumnSpan = columnCount;
            GridView1.Rows[0].Cells[0].Text = "无内容";
            GridView1.RowStyle.HorizontalAlign = System.Web.UI.WebControls.HorizontalAlign.Center;
        }

    }DataList操作：
private void fill_dlProducts(string a)
    {
        string strSel = "select * from sp_gl ";
        SqlDataAdapter da = new SqlDataAdapter(strSel, con.con);
        dtTable = new DataTable();
        da.Fill(dtTable);
        this.dlProducts.DataSource = dtTable;
        this.dlProducts.DataBind();

        if (dtTable.Rows.Count == 0)
        {
            dtTable.Rows.Add(dtTable.NewRow());
            dlProducts.DataSource = dtTable;
            dlProducts.DataBind();
            Label l = new Label();
            l.Text = "对不起,没有您所查询的产品!";
            dlProducts.Items[0].Controls.Clear();
            dlProducts.Items[0].Controls.Add(l);
        }
    }