问新手在使用GridView时遇到了问题

EN

<form id="form1" runat="server">
<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:CUBE %>" 
    ProviderName="<%$ ConnectionStrings:CUBE.ProviderName %>" 
    SelectCommand="SELECT csono, citemno, nordqty, nseq, nprice, cdescript, nsalesamt FROM dbo.sostrs WHERE (LTRIM(csono) = @csono) ORDER BY nseq">
    <selectparameters>
        <asp:controlparameter name="csono" controlid="frmSONum" propertyname="Text"/>
    </selectparameters>
</asp:SqlDataSource>

<asp:TextBox ID="frmSONum" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" />

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
    DataSourceID="SqlDataSource1" CellPadding="4" ForeColor="#333333" 
    GridLines="None">
    <AlternatingRowStyle BackColor="White" />
    <Columns>
        <asp:BoundField DataField="citemno" HeaderText="citemno" 
            SortExpression="citemno" />
        <asp:BoundField DataField="cdescript" HeaderText="cdescript" 
            SortExpression="cdescript" />
        <asp:BoundField DataField="nordqty" HeaderText="nordqty" 
            SortExpression="nordqty" />
        <asp:BoundField DataField="nprice" HeaderText="nprice" 
            SortExpression="nprice" />
        <asp:BoundField DataField="nsalesamt" HeaderText="nsalesamt" 
            SortExpression="nsalesamt" />
    </Columns>
    <EditRowStyle BackColor="#7C6F57" />
    <FooterStyle BackColor="#1C5E55" Font-Bold="True" ForeColor="White" />
    <HeaderStyle BackColor="#1C5E55" Font-Bold="True" ForeColor="White" />
    <PagerStyle BackColor="#666666" ForeColor="White" HorizontalAlign="Center" />
    <RowStyle BackColor="#E3EAEB" />
    <SelectedRowStyle BackColor="#C5BBAF" Font-Bold="True" ForeColor="#333333" />
    <SortedAscendingCellStyle BackColor="#F8FAFA" />
    <SortedAscendingHeaderStyle BackColor="#246B61" />
    <SortedDescendingCellStyle BackColor="#D4DFE1" />
    <SortedDescendingHeaderStyle BackColor="#15524A" />
</asp:GridView>
</form>

ERROR [42000] [Microsoft][ODBC SQL Server Driver][SQL Server]Must declare the variable '@csono'.