DropDownList做级联菜单报错

Question

DropDownList做级联菜单
国家-省-市 
选择国家时就报错
Eval()、XPath() 和 Bind() 这类数据绑定方法只能在数据绑定控件的上下文中使用。
怎么解决啊

Answer 1

数据使用ObjectDataSource 帮定

Answer 2

全部数据帮订，怎么贴代码啊，有碰到过类似情况的吗？<tr>
                                                <td  style="padding-top:20px">
                                                    <table>
                                                        <tr>
                                                            <td>
                                                    国家
                                                </td>
                                                <td>
                                                    <asp:ObjectDataSource ID="ObjectDataSourceCountry" runat="server"
                                         SelectMethod="QueryCountry" TypeName="Estate"></asp:ObjectDataSource>
                                                    <asp:DropDownList ID="DropDownListCountry" runat="server" DataSourceID="ObjectDataSourceCountry"
                                                        DataTextField="CountryName" DataValueField="CountryID"  AutoPostBack="True" OnSelectedIndexChanged="DropDownListCountry_SelectedIndexChanged">
                                                    </asp:DropDownList></td>
                                                        </tr>
                                                        <tr>
                                                <td>
                                                    省
                                                </td>
                                                <td>
                                                     <asp:ObjectDataSource ID="ObjectDataSourceState" runat="server"
                                         SelectMethod="QueryState" TypeName="Estate">
                                         <SelectParameters>
                                             <asp:ControlParameter ControlID="DropDownListCountry" Name="CountryID" PropertyName="SelectedValue"
                                                 Type="Int32" />
                                         </SelectParameters>
                                     </asp:ObjectDataSource>
                                                    <asp:DropDownList ID="DropDownListState" runat="server" DataSourceID="ObjectDataSourceState"
                                                        DataTextField="StateName" DataValueField="StateID" AutoPostBack="True" OnDataBound="DropDownListState_DataBound" OnSelectedIndexChanged="DropDownListState_SelectedIndexChanged">
                                                    </asp:DropDownList></td>
                                            </tr>
                                             <tr>
                                                <td>
                                                     市
                                                </td>
                                                <td>
                                                    &nbsp;&nbsp;
                                                    <asp:ObjectDataSource ID="ObjectDataSourceCity" runat="server"
                                         SelectMethod="QueryCity" TypeName="Estate">
                                         <SelectParameters>
                                             <asp:ControlParameter ControlID="DropDownListState" Name="StateID" PropertyName="SelectedValue"
                                                 Type="Int32" />
                                         </SelectParameters>
                                     </asp:ObjectDataSource>
                                                    <asp:DropDownList ID="DropDownListCity" runat="server" DataSourceID="ObjectDataSourceCity"
                                                        DataTextField="CityName" DataValueField="CityID" SelectedValue='<%# Bind("CityID") %>' AutoPostBack="True">
                                                    </asp:DropDownList></td>
                                            </tr>

Answer 3

国家 一个DropDownList
省 一个 DropDownList  参数为国家的ID
市 一个DropDownList  参数为 省的ID
全部数据帮定Objectdatasource

Answer 4

把asp.net的dropdownList做成菜单，好像不错。有做过的没？
他的menu不能跨越frame。