母版页中的ModalpopupExtender

Question

我在母版页上添加了一个modalpopup时遇到了一个小问题。弹出窗口从页面调用时工作正常，但继承的页面无法打开任何其他modalpopup！当我从母版页中删除modalpopup时，modals开始再次工作。

主页modalpopupextender如下所示

<asp:ContentPlaceHolder ID="ContentPlaceHolder2" runat="server">
        </asp:ContentPlaceHolder>
        <asp:LinkButton ID="fakeTarget" runat="server" Text=""></asp:LinkButton>

        <ajaxToolkit:ModalPopupExtender ID="PopupMaster" runat="server"
            TargetControlID="fakeTarget"
            PopupControlID="PopupMasterPanel"
            DropShadow="true"
            OkControlID="KapatUst"
            PopupDragHandleControlID="headerpn" BackgroundCssClass="MasterModalPopupBG">
            <Animations>
                <OnShown>
                    <FadeIn Duration="0.8" Fps="40" />
                </OnShown>
                <OnHiding>

                    <FadeOut Duration="0.8" Fps="40" />
                </OnHiding>
            </Animations>
        </ajaxToolkit:ModalPopupExtender>
        <%--<div id="headerpn" title="MY Header" runat="server"> </div>--%>
        <asp:Panel ID="PopupMasterPanel" runat="server">
            <div class="MasterPopupBodyBaslik" id="MasterPopupHeaderDiv" runat="server">

            </div>
            <div class="MasterPopupBody" id="MasterPopupBodyDiv" runat="server">
            </div>

        </asp:Panel>