*******TabContainer与ControlParameter的问题请教


<ajaxToolkit:TabContainer runat="server" ID="Tabs" Height="410px" ActiveTabIndex="0" Width="820px">
    <ajaxToolkit:TabPanel runat="server" ID="TabPanel1" HeaderText="当前录入">
       <ContentTemplate>
        ......
       </ContentTemplate>
    </ajaxToolkit:TabPanel>      <ajaxToolkit:TabPanel runat="server" ID="TabPanel2" HeaderText="事后录入">
       <ContentTemplate>
編號：
<asp:SqlDataSource runat="server" id="sdsTSNO" ConnectionString="<%$ConnectionStrings:ConnectionPub%>"></asp:SqlDataSource>
<asp:DropDownList runat="server" ID="ddlTSNO" DataSourceID="sdsTSNO" DataTextField="CourseName" DataValueField="AnnualID" AutoPostBack="true"/>
       </ContentTemplate>
    </ajaxToolkit:TabPanel>  
</ajaxToolkit:TabContainer><asp:SqlDataSource runat="server" id="sdsEmployee" ConnectionString="<%$ConnectionStrings:ConnectionJobTS%>">
<selectparameters>
   <asp:controlparameter name="annualid" controlid="Tabs$TabPanel2$ddlTSNO" propertyname="SelectedValue" ConvertEmptyStringToNull="false"/>
</selectparameters>
<deleteparameters>
   <asp:controlparameter name="uid" controlid="txtEmpNO" propertyname="Text" ConvertEmptyStringToNull="false"/>
</deleteparameters>
</asp:SqlDataSource>
<asp:GridView runat="server" id="gvEmployee" DataSourceID="sdsEmployee"/>为什么controlparameter不能像下面UpdatePanel中的方式一样用,而会报错：Could not find control 'ddlTSNO' in ControlParameter 'annualid'.
<asp:AsyncPostBackTrigger ControlID= "TabContainer$TabPanel1$btnUpdate"/>