Hi i am a newbie here, and i have learn to develop at Training Videos

but i got a problem when i try to add a gridview at helloweb section, and use sqldatabase to connect the App_Data\test.mdf, it is said "An attempt to attach an auto-named database for file D:\website\acmmp\Web\lytest1\App_Data\test.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share"

the helloweb source code below here  

<%@ Control Language="C#" AutoEventWireup="false" CodeBehind="helloweb.ascx.cs" Inherits="lytest.Web.UI.hellowebModule" %>

<portal:mojoPanel ID="mp1" runat="server" ArtisteerCssClass="art-Post" RenderArtisteerBlockContentDivs="true">
<mp:CornerRounderTop id="ctop1" runat="server" />
<asp:Panel ID="pnlWrapper" runat="server" cssclass="art-Post-inner panelwrapper helloweb">
<portal:ModuleTitleControl EditText="Edit" EditUrl="~/helloweb/hellowebEdit.aspx" runat="server" id="TitleControl" />
<portal:mojoPanel ID="MojoPanel1" runat="server" ArtisteerCssClass="art-PostContent">
<asp:Panel ID="pnlhelloweb" runat="server" CssClass="modulecontent">

<div class="settingrow">
        This will soon be the entry point to the helloweb.<br />
       
</div>

</asp:Panel>
</portal:mojoPanel>
<div class="cleared">
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
        DataSourceID="SqlDataSource1">
        <Columns>
            <asp:BoundField DataField="name" HeaderText="name" SortExpression="name" />
            <asp:BoundField DataField="age" HeaderText="age" SortExpression="age" />
        </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="SqlDataSource1" runat="server"
        ConnectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=D:\website\acmmp\Web\lytest1\App_Data\test.mdf;Integrated Security=True;User Instance=True"
        SelectCommand="SELECT * FROM [name]"></asp:SqlDataSource>
    </div>
</asp:Panel>
<mp:CornerRounderBottom id="cbottom1" runat="server" />
</portal:mojoPanel>