C# – Updatepanel with gridview inside doesn’t fire events

i've a usercontrol with a gridview inside an updatepanel.

I've tried to trigger all the grid events because the master page should never post backed when i'm working on the gridview, but it doesn't work. The master page is always post backed!

What i can do?

This is myuser control asp.net code:

<asp:UpdatePanel ID="upFeatureCustomer" runat="server" ChildrenAsTriggers="true" >
<ContentTemplate>
<asp:GridView ID="gvFeatureCustomer" runat="server" DataKeyNames="Id"  
        AutoGenerateColumns="False" ClientIDRowSuffix="Id" 
    OnRowDataBound="dtgdResult_RowDataBound" ClientIDMode="Static" 
        ShowHeader="false">
    <Columns>
        <asp:TemplateField HeaderText="Nome" FooterText="Nome" SortExpression="Name">
            <ItemTemplate>
                <asp:DropDownList ID="ddlName" ClientIDMode="Predictable" runat="server" DataValueField="id" DataTextField="Name">
                </asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Valore" FooterText="Valore" SortExpression="Value">
            <ItemTemplate>
                <asp:TextBox id="txtValue" AutoPostBack="true" runat="server" CssClass="auto-feature" OnTextChanged="txtValue_TextChanged"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
         <asp:TemplateField HeaderText="Delete" FooterText="Delete" Visible="true" HeaderStyle-Width="25"
                ItemStyle-HorizontalAlign="Center">
                <ItemTemplate>
                    <asp:HyperLink ID="Delete" runat="server" NavigateUrl='<%# DataBinder.Eval(Container, "DataItem.Id", "javascript:openDeleteDialog(\"{0}\");")%>'
                        ImageUrl="~/images/delete2.png" ToolTip="Delete">
                    </asp:HyperLink>
                </ItemTemplate>
            </asp:TemplateField>
    </Columns>
</asp:GridView>

</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="DataBinding" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="DataBound" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="Disposed" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="Init" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="Load" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="PageIndexChanged" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="PageIndexChanging" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="PreRender" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowCancelingEdit" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowCommand" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowCreated" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowDataBound" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowDeleted" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowDeleting" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowEditing" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowUpdated" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="RowUpdating" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="SelectedIndexChanged" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="SelectedIndexChanging" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="Sorted" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="Sorting" />
<asp:AsyncPostBackTrigger ControlID="gvFeatureCustomer" EventName="Unload" />
</Triggers>

</asp:UpdatePanel> 

ScriptManager is located inside the masterpage.
Thank you.