dropdownlist问题

<asp:Panel id="PanelDataGridMD" style="OVERFLOW: auto" runat="server" Width="100%" Height="280px"> 
<asp:DataGrid id="ZC0000000000606" runat="server" Width="100%" CellPadding="1" Font-Size="9" ForeColor="Navy"
BackColor="#ccffff" SelectedItemStyle-BackColor="#ccffcc" BorderWidth="3px" AutoGenerateColumns="False"
EnableViewState="true" BorderStyle="Double" BorderColor="RoyalBlue">
<SelectedItemStyle Font-Size="9" Font-Bold="False" ForeColor="Navy" BackColor="#ccffff"></SelectedItemStyle>
<AlternatingItemStyle BackColor="#99ccff" ForeColor="Navy" Font-Size="9"></AlternatingItemStyle>
<HeaderStyle Font-Size="10" Font-Bold="True" ForeColor="Yellow" BackColor="RoyalBlue"></HeaderStyle>
<FooterStyle Font-Size="9" ForeColor="#330099" BackColor="RoyalBlue"></FooterStyle>
<Columns>
<asp:BoundColumn DataField="DocId" Visible="False" ReadOnly="True"></asp:BoundColumn>
<asp:BoundColumn DataField="Num" ReadOnly="True" HeaderText="编号" HeaderStyle-HorizontalAlign="Center"
ItemStyle-HorizontalAlign="Center" HeaderStyle-Width="40px"></asp:BoundColumn>
<asp:TemplateColumn HeaderText="申请列别" HeaderStyle-HorizontalAlign="Center" FooterStyle-Font-Size="9">
<ItemTemplate>
<asp:DropDownList ID="COLCTRL1" Runat="server" EnableViewState="True" Height="50" Width="100%" Font-Size="9"  BorderWidth="5"></asp:DropDownList>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="申请内容" HeaderStyle-HorizontalAlign="Center" FooterStyle-Font-Size="9">
<ItemTemplate>
<asp:TextBox ID="COLCTRL2" Runat="server" Width="100%" Font-Size="9" Height="50"></asp:TextBox>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="其他" HeaderStyle-HorizontalAlign="Center" FooterStyle-Font-Size="9">
<ItemTemplate>
<asp:TextBox ID="COLCTRL3" Runat="server" Width="100%" Font-Size="9" Height="50"></asp:TextBox>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
<PagerStyle HorizontalAlign="Center" ForeColor="#330099" BackColor="#FFFFCC"></PagerStyle>
</asp:DataGrid>
</asp:Panel>
当申请类别，控件COLCTRL1下拉选择内容以后，后面COLCTRL2申请内容里才能填写内容。否则锁死没办法填写。
这段程序应该怎么写 --------------------编程问答-------------------- void   DropDownList1_SelectedIndexChanged(Object   sender,   EventArgs   e)
        {
                    DropDownList   ddl   =   (DropDownList)sender;
                    Response.Write(ddl.SelectedItem.Text);
        }
<asp:DropDownList   id= "DropDownList1 "
                    OnSelectedIndexChanged= "DropDownList1_SelectedIndexChanged "
                    AutoPostBack= "True "
                    runat= "server "/>
--------------------编程问答-------------------- 还有人帮忙不 --------------------编程问答-------------------- --------------------编程问答--------------------

补充：.NET技术 ,  组件/控件开发