Asp.net 将控件添加到现有自定义验证

我有以下问题： 我的ASP代码是下一个：

<span class="required">*</span> <%=LabelsFactory.Current.Get("FormLabels", "RequiredFields")%><asp:ValidationSummary ID="ValidationSummary1" runat="server" ValidationGroup="ValidationGroup1" CssClass="required" DisplayMode="BulletList" ForeColor="" /><asp:CustomValidator ID="cvGeneralError" runat="server" ValidationGroup="ValidationGroup1" Display="None" ErrorMessage='<%# LabelsFactory.Current.Get("FormLabels", "GeneralError") %>'></asp:CustomValidator><asp:Panel ID="pFormElements" runat="server"></asp:Panel><asp:Panel ID="pValidators" runat="server"></asp:Panel><fieldset><asp:Button ID="Button1" runat="server" Text="Button" ValidationGroup="ValidationGroup1" OnClick="Button1_Click" CssClass="button" /></fieldset>

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如果您有母版页，则需要首先访问父级，即占位符，然后才能找到控件：

ContentPlaceHolder cph =(ContentPlaceHolder)this.Master.FindControl("MainContent");
var control = (DropDownList)cph.FindControl("ddlList");

ContentPlaceHolder cph =(ContentPlaceHolder)this.Master.FindControl("MainContent");
var control = (DropDownList)cph.FindControl("ddlList");