页面更改事件中显示空数据文本

Question

我已经创建了一个gridview并绑定了它，我也给出了pageindexchanging事件，但是尽管数据库中有数据，但下一页仍显示空白数据文本。

protected void Page_Load(object sender, EventArgs e)
{
    if(!IsPostBack)
    {
        BindGrid();
    }

}
protected void BindGrid()
{
    SqlConnection con = new SqlConnection(strcon);
    con.Open();
    SqlCommand cmd = new SqlCommand("usp_GetOutDetails", con);
    cmd.CommandType = CommandType.StoredProcedure;
    SqlDataAdapter sda = new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    sda.Fill(ds);
    GridView1.DataSource = ds;
    GridView1.DataBind();
}
protected void Gridview1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    GridView1.PageIndex = e.NewPageIndex;
    GridView1.DataBind();

}

aspx

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
     Height="169px" Width="962px" style="margin-top: 15px" CellPadding="10" 

           CssClass="table table-bordered" AllowPaging="True" 
   OnPageIndexChanging="Gridview1_PageIndexChanging" EmptyDataText="No such record exists.!!!!" >

        <Columns>
            <asp:CommandField SelectText="Update" ShowSelectButton="True" />
         <asp:BoundField HeaderText="SA Number" DataField="SANo" />
             <asp:BoundField HeaderText="SA Date" DataField="SADate" DataFormatString="{0:dd/MM/yyyy}" />
             <asp:BoundField HeaderText="Customer Code" DataField="CustomerCode" />
            <asp:BoundField HeaderText="Customer Name" DataField="CustomerName" />
      </Columns>
         <HeaderStyle HorizontalAlign="Center" />
         <PagerSettings Mode="Numeric" PageButtonCount="10" FirstPageText="First" LastPageText="Last"/>  
          <PagerStyle HorizontalAlign = "Left" CssClass = "GridPager" />
</asp:GridView>