Export to csv in c# ASP.NET working fine but when used in Scriptmanager stops working

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C#3.5

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I have to use export to csv in asp.net in c#. Its working fine but when used with script manager it stops working.
I used

<asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:Panel ID="Panel1" runat="server" Height="460px" Width="842px">
            <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
                DataKeyNames="name" DataSourceID="SqlDataSource1" Height="388px" Width="350px">
                <Columns>
                    <asp:BoundField DataField="name" HeaderText="name" ReadOnly="True"
                        SortExpression="name" />
                    <asp:BoundField DataField="pass" HeaderText="pass" SortExpression="pass" />
                    <asp:BoundField DataField="roll" HeaderText="roll" SortExpression="roll" />
                </Columns>
            </asp:GridView>
            <asp:SqlDataSource ID="SqlDataSource1" runat="server"
                ConnectionString="<%$ ConnectionStrings:abcConnectionString %>"
                SelectCommand="SELECT DISTINCT * FROM [rr]"></asp:SqlDataSource>
            <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click"
                Width="153px" />
        </asp:Panel>
        <asp:Panel ID="Panel2" runat="server">
            <asp:Button ID="Button2" runat="server" onclick="Button2_Click" Text="Button"
                Width="153px" />
            </asp:Panel>
    </ContentTemplate>
        </asp:UpdatePanel>

Actually when gridview.rows.count is executed its gives 0. Its unable to count the rows.
Any suggestion will be heartily accepted.