Formview doesn't change Mode

Question

When I try to change my formview to Edit, he stays in de ReadOnlyMode. I can't figure out why. This is my code.

<asp:FormView ID="fvDetailOrder" runat="server" AllowPaging="True" DataKeyNames="ID" OnModeChanging="fvDetailOrder_ModeChanging">
    <EditItemTemplate>
      // I want to see this, when I click edit
        <asp:LinkButton ForeColor="#003366" ID="UpdateButton" runat="server" CausesValidation="True"
            CommandName="Update" Text="Update" />
        &nbsp;<asp:LinkButton ForeColor="#003366" ID="UpdateCancelButton" runat="server"
            CausesValidation="False" CommandName="Cancel" Text="Cancel" />
    </EditItemTemplate>
    <InsertItemTemplate>
       Insert here
        <asp:LinkButton ForeColor="#003366" ID="InsertButton" runat="server" CausesValidation="True"
            CommandName="Insert" Text="Insert" />
        &nbsp;<asp:LinkButton ForeColor="#003366" ID="InsertCancelButton" runat="server"
            CausesValidation="False" CommandName="Cancel" Text="Cancel" />
    </InsertItemTemplate>
    <ItemTemplate>
        Read only
        <asp:LinkButton ForeColor="#003366" ID="EditButton" runat="server" CausesValidation="False"
            CommandName="Edit" Text="Edit" />
        &nbsp;<asp:LinkButton ForeColor="#003366" ID="DeleteButton" runat="server" CausesValidation="False"
            CommandName="Delete" Text="Delete" OnClientClick="return confirm('Are you certain you want to delete this product?');" />
        &nbsp;<asp:LinkButton ForeColor="#003366" ID="NewButton" runat="server" CausesValidation="False"
            CommandName="New" Text="New" />
    </ItemTemplate>
    <PagerStyle ForeColor="#003366" />
</asp:FormView>

Eventhandler

protected void fvDetailOrder_ModeChanging(Object sender, FormViewModeEventArgs e)
{
    fvDetailOrder.ChangeMode(e.NewMode);
}