FormView不显示任何数据

Question

我有一个FormView控件，我只需要“编辑”模式。这是我的代码

<asp:FormView ID="fvProposal" runat="server" Visible="True" 
    DataSourceID="sdsProposal"
    DefaultMode="Edit">
    <EmptyDataTemplate>
        There is nothing to see here.
    </EmptyDataTemplate>
    <EditItemTemplate>
        <span class="AttributeLabel">Title:</span>
        <asp:TextBox ID="TitleTextBox" runat="server" Text='<%# Bind("Title") %>' />
        <asp:RequiredFieldValidator runat="server" ControlToValidate="TitleTextBox" CssClass="reqfield" Text="*Required field." />
        <br />
        <span class="AttributeLabel">Description:</span>
        <asp:TextBox ID="DescriptionTextBox" runat="server" TextMode="MultiLine" Text='<%# Bind("Description") %>' Width="40%" />
        <br />
        <span class="AttributeLabel">Funding Agency:</span>
        <asp:TextBox ID="FundingAgencyTextBox" runat="server" Text='<%# Bind("FundingAgency") %>' />
        <asp:RequiredFieldValidator runat="server" ControlToValidate="FundingAgencyTextBox" CssClass="reqfield" Text="*Required field." />
        <br />
        <span class="AttributeLabel">Submit for review:</span>
        <asp:CheckBox ID="cbSubmit" runat="server" Checked='<%# Bind("Sub") %>'/> Check if you are ready to submit this proposal.
        <br />
        <span class="AttributeLabel">
            <asp:Button ID="UpdateButton" runat="server" CausesValidation="True" CommandName="Update" Text="Proceed" />
        </span>
        <asp:Button ID="UpdateCancelButton" runat="server" CausesValidation="False" CommandName="Cancel" Text="Cancel" PostBackUrl="MyProposals.aspx"/>
    </EditItemTemplate>
    <ItemTemplate>
        <asp:LinkButton ID="EditButton" runat="server" CausesValidation="False" CommandName="Edit" Text="Edit my information" CssClass="button"/><br/>
        <br/>
    </ItemTemplate>
</asp:FormView>
<asp:SqlDataSource ID="sdsProposal" runat="server" ConnectionString="<%$ ConnectionStrings:cnIRBSS %>"  
    SelectCommand="SELECT [Title], [Description], [FundingAgency] FROM [Proposal] WHERE ProposalID=@PID" 
    UpdateCommand="UPDATE [Title] SET [Title] = @Title, [Description] = @Description, [FundingAgency] = @FundingAgency, [Submitted] = @Sub WHERE [ProposalID] = @PID">
    <UpdateParameters>
        <asp:SessionParameter SessionField="ProposalID" Name="PID" />
        <asp:Parameter Name="Title" Type="String" />
        <asp:Parameter Name="Description" Type="String" />
        <asp:Parameter Name="FundingAgency" Type="String" />
        <asp:Parameter Name="Sub" Type="Boolean"/>
    </UpdateParameters>
    <SelectParameters>
        <asp:SessionParameter SessionField="PID" Name="ProposalID" />            
    </SelectParameters>
</asp:SqlDataSource>

我的问题是，即使来自SQLDataSource的相同查询在SQLSMS中返回正确的数据，FormView也不会显示数据。我错过了什么和/或做错了什么？