创建控件时出错，无法创建类型'cc1：TabContainer'，无法加载文件或程序集System.Web.extension，Version = 1.0.61025.0'

Question

创建控件时出错，无法创建类型＆＃39; cc1：TabContainer＆＃39;，无法加载文件或程序集System.Web.extension，Version = 1.0.61025.0＆＃39; 系统找不到指定的文件

我得到这个错误。你能告诉我哪里错了吗？为什么我不能在aspx中看到我的设计？

码

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<cc1:TabContainer runat="server" ID="Tab_Continer" ActiveTabIndex="0">
        <cc1:TabPanel ID="TabPnl_Project" runat="server">
            <HeaderTemplate>
                Keyword Position</HeaderTemplate>
            <ContentTemplate>

                <table>
                    <tr>
                        <td>
                            <asp:Label ID="lbl_Project" runat="server" Text="Project"></asp:Label>
                        </td>
                        <td>
                            <asp:DropDownList ID="ddlProject" runat="server" OnSelectedIndexChanged="ddlProject_SelectedIndexChanged"
                                AutoPostBack="true">
                            </asp:DropDownList>
                            <asp:RequiredFieldValidator Display="Dynamic" ID="RequiredFieldValidator3" runat="server"
                                ErrorMessage="*" ControlToValidate="ddlProject" ValidationGroup="ValPos"></asp:RequiredFieldValidator>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <asp:Label ID="lblLkeyword" runat="server" Text="Keyword"></asp:Label>
                        </td>
                        <td>
                            <asp:DropDownList ID="ddlKeyword" runat="server" OnSelectedIndexChanged="ddlKeyword_SelectedIndexChanged"
                                AutoPostBack="true">
                            </asp:DropDownList>
                            <asp:RequiredFieldValidator Display="Dynamic" ID="RequiredFieldValidator2" runat="server"
                                ErrorMessage="*" ControlToValidate="ddlKeyword" ValidationGroup="ValPos"></asp:RequiredFieldValidator>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <asp:Label ID="lblPos" runat="server" Text="Position"></asp:Label>
                        </td>
                        <td>
                            <asp:TextBox ID="txtPostion" runat="server"></asp:TextBox>
                            <asp:RequiredFieldValidator Display="Dynamic" ID="RequiredFieldValidator1" runat="server"
                                ErrorMessage="*" ControlToValidate="txtPostion" ValidationGroup="ValPos"></asp:RequiredFieldValidator>
                            <asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" ControlToValidate="txtPostion"
                                ValidationExpression="^[0-9]{0,3}$" ErrorMessage="*" ValidationGroup="ValPos"
                                ToolTip="Enter only numeric values" Display="Dynamic"></asp:RegularExpressionValidator>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <asp:Label ID="lbl_Date" runat="server" Text="Date"></asp:Label>
                        </td>
                        <td>
                            <asp:TextBox ID="txtDate" runat="server"></asp:TextBox>
                            <cc1:CalendarExtender ID="Ajax_Calend" runat="server" TargetControlID="txtDate">
                            </cc1:CalendarExtender>
                            <asp:RequiredFieldValidator Display="Dynamic" ID="Valid_Req_DtFrm" runat="server"
                                ErrorMessage="*" ControlToValidate="txtDate" ValidationGroup="ValPos"></asp:RequiredFieldValidator>
                        </td>
                    </tr>
                    <tr>
                        <td>
                        </td>
                        <td align="left">
                            <asp:Button ID="btn_Submit" runat="server" Text="Submit" ValidationGroup="ValPos"
                                OnClick="btn_Submit_Click" CssClass="button" />
                        </td>
                    </tr>
                    <tr>
                        <td>
                        </td>
                        <td align="left">
                            <asp:Label ID="LblMsg" runat="server" Font-Bold="true"></asp:Label>
                        </td>
                    </tr>
                </table>

            </ContentTemplate>
        </cc1:TabPanel>
        <cc1:TabPanel ID="Tab_Update" runat="server">
            <HeaderTemplate>
                Traffic</HeaderTemplate>
            <ContentTemplate>
                <asp:UpdatePanel ID="update12" runat="server">
                    <ContentTemplate>
                        <table>
                            <tr>
                                <td>
                                    <asp:Label ID="lblProject" runat="server" Text="Project"></asp:Label>
                                </td>
                                <td>
                                    <asp:DropDownList ID="ddl_Project" runat="server">
                                    </asp:DropDownList>
                                    <asp:RequiredFieldValidator Display="Dynamic" ID="RequiredFieldValidator4" runat="server"
                                        ErrorMessage="*" ControlToValidate="ddl_Project" ValidationGroup="ValTraffic"></asp:RequiredFieldValidator>
                                </td>
                            </tr>
                            <tr>
                                <td>
                                    <asp:Label ID="lblTraffic" runat="server" Text="Traffic"></asp:Label>
                                </td>
                                <td>
                                    <asp:TextBox ID="txtTarffic" runat="server"></asp:TextBox>
                                    <asp:RequiredFieldValidator Display="Dynamic" ID="RequiredFieldValidator5" runat="server"
                                        ErrorMessage="*" ControlToValidate="txtTarffic" ValidationGroup="ValTraffic"></asp:RequiredFieldValidator>
                                    <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="txtTarffic"
                                        ValidationExpression="^[0-9]{0,5}$" ErrorMessage="*" ToolTip="Enter only numeric values"
                                        ValidationGroup="ValTraffic" Display="Dynamic"></asp:RegularExpressionValidator>
                                </td>
                            </tr>
                            <tr>
                                <td>
                                    <asp:Label ID="Label1" runat="server" Text="Date"></asp:Label>
                                </td>
                                <td>
                                    <asp:TextBox ID="Txt_Date" runat="server"></asp:TextBox>
                                    <cc1:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="Txt_Date">
                                    </cc1:CalendarExtender>
                                    <asp:RequiredFieldValidator Display="Dynamic" ID="RequiredFieldValidator6" runat="server"
                                        ErrorMessage="*" ControlToValidate="Txt_Date" ValidationGroup="ValTraffic"></asp:RequiredFieldValidator>
                                </td>
                            </tr>
                            <tr>
                                <td>
                                </td>
                                <td align="left">
                                    <asp:Button ID="btnSave" runat="server" ValidationGroup="ValTraffic" Text="Submit"
                                        OnClick="btnSave_Click" CssClass="button" />
                                </td>
                            </tr>
                            <tr>
                                <td>
                                </td>
                                <td align="left">
                                    <asp:Label ID="lbl_Msg" runat="server" Font-Bold="true"></asp:Label>
                                </td>
                            </tr>
                        </table>
                    </ContentTemplate>
                </asp:UpdatePanel>
            </ContentTemplate>
        </cc1:TabPanel>
    </cc1:TabContainer>