Delete entry from gridview

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C#

ASP.NET

Gridview

I have gridview in which i am fetching records from database, i have two link buttons columns at the right side of my gridview columns. one is for view and second is for delete...i want when user click on the delete button then the corresponding record is delete.

<asp:GridView ID="gv_ads" runat="server" AutoGenerateColumns="False" 
                    onrowcommand="gv_ads_RowCommand" AllowPaging="True" 
                    OnPageIndexChanging="gv_ads_PageIndexChanging" CellPadding="4" 
                    ForeColor="#333333" GridLines="None" Width="998px" >
                    <AlternatingRowStyle BackColor="White" />
                   <Columns>
                           <asp:BoundField DataField="register_On" HeaderText="Register On" />
                           <asp:BoundField DataField="ad_id" HeaderText="Ad ID" />
                           <asp:BoundField DataField="category_name" HeaderText="Category" >
                           </asp:BoundField>
                           <asp:BoundField DataField="subcategory_name" HeaderText="Sub-Category" >
                           </asp:BoundField>
                           <asp:BoundField DataField="title" HeaderText="Ad Title" >
                           </asp:BoundField>
                           <asp:BoundField DataField="s_name" HeaderText="State" >
                           </asp:BoundField>
                           <asp:BoundField DataField="pincode" HeaderText="Pincode" />
                           
                           <asp:TemplateField HeaderText="View Ad">
                            <ItemTemplate>
                            <asp:LinkButton runat="server" ID="lnkView" CommandArgument='<%#Eval("ad_id") %>' CommandName="VIEW">View/Edit</asp:LinkButton>
                           </ItemTemplate>
                           </asp:TemplateField>

                           <asp:TemplateField HeaderText="Delete Ad">
                           <ItemTemplate>
                             <asp:LinkButton runat="server" ID="linkDelete" OnClientClick="return confirm('Are you sure you want to delete this entry?');" CommandArgument='<%#Eval("ad_id") %>' CommandName="DELETE">Delete</asp:LinkButton>
                           </ItemTemplate>
                           </asp:TemplateField>
                          
                   </Columns>
                    <FooterStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
                    <HeaderStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
                    <PagerStyle BackColor="#FFCC66" ForeColor="#333333" HorizontalAlign="Center" />
                    <RowStyle BackColor="#FFFBD6" ForeColor="#333333" />
                    <SelectedRowStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="Navy" />
                    <SortedAscendingCellStyle BackColor="#FDF5AC" />
                    <SortedAscendingHeaderStyle BackColor="#4D0000" />
                    <SortedDescendingCellStyle BackColor="#FCF6C0" />
                    <SortedDescendingHeaderStyle BackColor="#820000" />
                </asp:GridView>

protected void gv_ads_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "VIEW")
        {
            int index = Convert.ToInt32(e.CommandArgument);
            Response.Redirect("Ads_Details.aspx?ad_id=" + index);

        }
        else if (e.CommandName == "DELETE")
        {
            int index = Convert.ToInt32(e.CommandArgument);
            SqlCommand cmd = new SqlCommand("sps_deletead", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@useremail", ses);
            cmd.Parameters.AddWithValue("@ad_id", index);
            try
            {
                con.Open();
                cmd.ExecuteNonQuery();
                message = "Ad Deleted Successfully.";
                ClientScript.RegisterStartupScript(GetType(), "alert", "alert('" + message + "');", true);
                con.Close();
                BindGridview();
            }
            catch (Exception)
            {
                throw;
            }
        }
    }

when i click on delete button the record is deleted from database but error comes "The GridView 'gv_ads' fired event RowDeleting which wasn't handled."
My code is working fine but Why this error is coming.