drop down in gridview , data not inserted into database

<asp:GridView ID="GridView1" runat="server" AllowPaging="True"
    AutoGenerateColumns="False" DataSourceID="SqlDataSource1"
     DataKeyNames="TEMPLATES"
    DataMember="DefaultView" AllowSorting="True" BackColor="White"
    BorderColor="#DEDFDE" BorderStyle="None" BorderWidth="1px" CellPadding="4"
    ForeColor="Black" GridLines="Vertical" PageSize="25"  >
    <RowStyle BackColor="#F7F7DE" />
    <Columns>
        <asp:BoundField DataField="SPOC" HeaderText="SPOC" ReadOnly="true "
            SortExpression="SPOC" />
        <asp:BoundField DataField="MODULE" HeaderText="MODULE" ReadOnly="true"
            SortExpression="MODULE" />
        <asp:HyperLinkField HeaderText="TEMPLATES" DataNavigateUrlFields ="TEMP"
            DataNavigateUrlFormatString= "/erp/modules/{0}" DataTextField="TEMPLATES"
            NavigateUrl="~/login/erp/modules/{0}" />

        <asp:TemplateField HeaderText="ASSIGNED" SortExpression="ASSIGNED">
        <ItemTemplate >
         <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true"
        DataSourceID="SqlDataSource25a" DataTextField="STAFF" DataValueField="MOBILE"
                onselectedindexchanged="DropDownList1_SelectedIndexChanged">
    </asp:DropDownList>
    <asp:SqlDataSource ID="SqlDataSource25a" runat="server"
        ConnectionString="<%$ ConnectionStrings:constr %>"
        ProviderName="<%$ ConnectionStrings:constr.ProviderName %>"
        SelectCommand="SELECT &quot;STAFF&quot;,&quot;MOBILE&quot; FROM &quot;LOGIN1&quot;">
    </asp:SqlDataSource>
</ItemTemplate>

        </asp:TemplateField>

        <asp:TemplateField HeaderText="CONTACT" SortExpression="CONTACT">

            <ItemTemplate>
                <asp:Label ID="lbl_cont" runat="server"></asp:Label>

                        <%--<asp:TextBox ID="TextBox1" runat="server"
                            Text='<%# Bind("ACCOUNT_CODING_MATRIX_SK") %>'></asp:TextBox>--%>

            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="COMPLETED" HeaderText="COMPLETED"
            SortExpression="COMPLETED" />
        <asp:BoundField DataField="MAILED_SPOC" HeaderText="MAILED_SPOC"
            SortExpression="MAILED_SPOC" />
        <asp:BoundField DataField="MAILED_CIROFF" HeaderText="MAILED_CIROFF"
            SortExpression="MAILED_CIROFF" />
        <asp:BoundField DataField="REMARKS" HeaderText="REMARKS"
            SortExpression="REMARKS" />
        <asp:CommandField ShowEditButton="True" />
    </Columns>
    <FooterStyle BackColor="#CCCC99" />
    <PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
    <SelectedRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
    <HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
    <AlternatingRowStyle BackColor="White" />
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
    ConnectionString="<%$ ConnectionStrings:constr %>"
    ProviderName="<%$ ConnectionStrings:constr.ProviderName %>"

    SelectCommand="SELECT * FROM ERPUPD"
                UpdateCommand="UPDATE ERPUPD SET &quot;ASSIGNED&quot; = :ASSIGNED, &quot;CONTACT&quot; = :CONTACT, &quot;COMPLETED&quot; = :COMPLETED, &quot;MAILED_SPOC&quot; = :MAILED_SPOC, &quot;MAILED_CIROFF&quot; = :MAILED_CIROFF, &quot;REMARKS&quot; = :REMARKS WHERE (&quot;TEMPLATES&quot; = :TEMPLATES)">
    <UpdateParameters>
        <asp:Parameter Name="ASSIGNED" />
        <asp:Parameter Name="CONTACT" />
        <asp:Parameter Name="COMPLETED" />
        <asp:Parameter Name="MAILED_SPOC" />
        <asp:Parameter Name="MAILED_CIROFF" />
        <asp:Parameter Name="REMARKS" />
        <asp:Parameter Name="TEMPLATES" />
    </UpdateParameters>
</asp:SqlDataSource>