用前台代码对select进行变更后ValidatorCalloutExtender失效如何解决？

[windgod]

前台:
$(".SelectProvince").change(function() {
$.ajax({
//初始化FixSiteCity列表
})
})

<select id="FixSiteProvince" class="SelectProvince" runat="server">
<option>北京</option>
<option>上海</option>
</select>

<select id="FixSiteCity" class="SelectCity" runat="server">
<option></option>
</select>

<asp:RequiredFieldValidator ID="RequiredFieldValidator9" runat="server" ErrorMessage="<div class='ErrorMessageCss'>地点不能为空！</div>"
Display="none" ControlToValidate="FixSiteCity" ValidationGroup="DoorValidationGroup"></asp:RequiredFieldValidator>
<cc1:ValidatorCalloutExtender ID="ValidatorCalloutExtender9" runat="server" TargetControlID="RequiredFieldValidator9"
HighlightCssClass="HighlightCssClass">
</cc1:ValidatorCalloutExtender>



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前台代码变更FixSiteCity内容后ValidatorCalloutExtender失效，如何解决？