Update not firing in GridView

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C#

ASP.NET

SQL

VS2010

<My GridView is binded to my database via SqlDataSource. The name of my database is gsi_swift_audit and has the primary key known as index_n.

The search function using postback is working fine and I have set Auto generate Edit Button = "True" and is able to click that to give me "Update and Cancel". The cancel button works fine, however when I click update, nothing is being updated into my database or rather nothing happens.

Here are my codes -

.aspx (for my select/update command and update parameters, the filter parameter is for my search function):

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
                    <ContentTemplate>

                        <asp:GridView ID="GridView1" runat="server" 
                            
                            AllowPaging="True" AllowSorting="True"  AutoGenerateEditButton="True" AutoGenerateColumns="False" BackColor="White" BorderColor="#999999" BorderWidth="1px" CellPadding="3" DataSourceID="SqlDataSource1" GridLines="Vertical" DataKeyNames="INDEX_N" OnSelectedIndexChanged="GridView1_SelectedIndexChanged">
                            
                            <AlternatingRowStyle BackColor="#DCDCDC" />
                            <Columns>
                                <asp:BoundField DataField="MSG_ID" HeaderText="MSG_ID" SortExpression="MSG_ID" ReadOnly="true"/>
                                <asp:BoundField DataField="ACTION_IND" HeaderText="ACTION_IND" SortExpression="ACTION_IND" />
                                <asp:BoundField DataField="ACTION_DATE" HeaderText="ACTION_DATE" SortExpression="ACTION_DATE" />
                                <asp:BoundField DataField="USERNAME" HeaderText="USERNAME" SortExpression="USERNAME" />
                                <asp:BoundField DataField="INDEX_N" HeaderText="INDEX_N" ReadOnly="True" SortExpression="INDEX_N" />
                            </Columns>
                            <FooterStyle BackColor="#CCCCCC" ForeColor="Black" />
                            <HeaderStyle BackColor="#000084" Font-Bold="True" ForeColor="White" />
                            <PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
                            <RowStyle BackColor="#EEEEEE" ForeColor="Black" />
                            <SelectedRowStyle BackColor="#008A8C" Font-Bold="True" ForeColor="White" />
                            <SortedAscendingCellStyle BackColor="#F1F1F1" />
                            <SortedAscendingHeaderStyle BackColor="#0000A9" />
                            <SortedDescendingCellStyle BackColor="#CAC9C9" />
                            <SortedDescendingHeaderStyle BackColor="#000065" />
                        </asp:GridView>
                        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:gsiadmin %>" ProviderName="<%$ ConnectionStrings:gsiadmin.ProviderName %>" 
                            UpdateCommand="UPDATE GSI_SWIFT_AUDIT SET ACTION_IND = @ACTION_IND, ACTION_DATE = @ACTION_DATE, USERNAME = @USERNAME WHERE INDEX_N = @INDEX_N"
                            SelectCommand="SELECT * FROM "GSI_SWIFT_AUDIT"" FilterExpression="MSG_ID = {0}">
                            <FilterParameters>
                                <asp:ControlParameter Name="txtsearchMSGID" ControlID="txtsearchMSGID" PropertyName="Text" />
                            </FilterParameters>
                            <UpdateParameters>
                                <asp:Parameter  Name="ACTION_IND" />
                                <asp:Parameter  Name="ACTION_DATE" />
                                <asp:Parameter  Name="USERNAME" />
                            </UpdateParameters>
                        </asp:SqlDataSource>
                    </ContentTemplate>
                    <Triggers>
                        <asp:AsyncPostBackTrigger ControlID="txtsearchMSGID" EventName="TextChanged" />
                        <asp:AsyncPostBackTrigger ControlID="GridView1" />
                    </Triggers>
                </asp:UpdatePanel>

I'm new to coding so I hope I will be able to solve this soon! :)