ModalPopUpExtender没有显示弹出窗口

Question

我有一个modalpopUpExtender并尝试弹出ATM的列表  以下代码显示ASP面板我想要弹出窗口

<asp:Panel ID="pnlBanks" CssClass="atmBnkPopup" runat="server" meta:resourcekey="pnlBanksResource1">
        <div id="pnlBanksCnt" style="display: none;">
            <h2 class="sectionHeading">
                <asp:Literal ID="litATMPaymentHeader" runat="server" meta:resourcekey="litATMPaymentHeaderResource1"
                    Text="ATM Payment (Indonesia)" />
            </h2>
            <asp:Literal ID="litATMPaymentText" runat="server" meta:resourcekey="litATMPaymentTextResource1" />
            <br />
            <div style="text-align: center;">
                <asp:LinkButton ID="lbCloseBanks" runat="server" meta:resourcekey="lbCloseBanksResource1"
                    Text="&lt;img 
                        alt=&quot;Close&quot; src=&quot;images/btn/btn-close.gif&quot; __designer:mapid=&quot;5f&quot; /&gt;" />
            </div>
        </div>
         <asp:Button ID="btnBanks" runat="server" Style="display: none;" meta:resourcekey="btnBanksResource1" />
    </asp:Panel>

    <cc1:ModalPopupExtender ID="mpeBanks" runat="server" TargetControlID="btnBanks" CancelControlID="lbCloseBanks"
        PopupControlID="pnlBanks" BackgroundCssClass="modalBackground" DynamicServicePath=""
        Enabled="True" />

在Aspx页面中，尝试调用JavaScript以弹出屏幕

<p>
  <asp:Literal ID="litATMBanks" runat="server" Text="To view the banks at which we accept ATM payment," meta: resourcekey="litATMBanksResource1" />
  <a href="javascript:ShowBankList();">
    <asp:Literal ID="litATMBanksLink" runat="server" Text="click here" meta: resourcekey="litATMBanksLinkResource1" />
  </a>
</p>

这是我的Java脚本

function ShowBankList() {
  var modal = $find("mpeBanks");
  if (modal) {
    $("pnlBanksCnt").style.display = "block";

    modal.show();
  }
}

我将Modal视为null。 我不确定代码中缺少什么。为什么$找不到元素