PARTIAL POSTBACK

I am a newbie and uptill now i have learned a lot from google however i've now stuck. I've constructed a dropdown list which includes three different selected items which display / hides the textboxes by selecting one of them. When the 'Branch Name' is selected, Textbox5 and 6 must be dissapeared with a partial postback. The code attached yet dissapears Textbox5 only, which doesn't fulfill my need.

When I tried to write the below mentioned lines in my code after the Last line. , it throws an error for closing the tag. I made another update panel 2 but i recieved an error i.e ""An extender can't be in a various UpdatePanel than the control it extends" . Will appreciate your help. Actual Code can be seen below.

</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTriggerControlID="DropDownList2"EventName="SelectedIndexChanged"/>
</Triggers>
</asp:UpdatePanel>

CODE

<asp:UpdatePanelID="UpdatePanel1"runat="server"UpdateMode="Conditional"ChildrenAsTriggers="False">
<ContentTemplate>
<asp:TextBoxID="TextBox5"runat="server"Height="17px"Width="104px"BackColor="#FFFF99"Font-Names="Calibri"></asp:TextBox>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTriggerControlID="DropDownList2"EventName="SelectedIndexChanged"/>
</Triggers>
</asp:UpdatePanel>
</td>
<td>
&nbsp;</td>
</tr>
<tr>
<tdclass="auto-style9"><asp:LabelID="Label7"runat="server"Font-Bold="True"Font-Size="Medium"Text="Complain Date"style="font-size:small"></asp:Label>
</td>
<tdclass="auto-style8">
<asp:TextBoxID="TextBox4"runat="server"Height="17px"Width="104px"OnTextChanged="TextBox2_TextChanged"BackColor="#FFFF99"Font-Names="Calibri"></asp:TextBox>