Dropdownlist in GridView EditItemTemplate Error: Visual Studio 2005

Dropdownlist in GridView EditItemTemplate Error:

'cboBrokerAccount' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value

I have a DropDownList in the EditItemTemplate and a Label in the ItemTemplate.

The label text is supposed to the display column of the DropDownList (DataTextField="AccountID" )

The dropdownlist datasource SQL is simply
SelectCommand="SELECT [AccountID], [AccountKey] FROM [Account] WHERE ([UserID] = @UserID) ORDER BY [AccountID]  ">

The DroppDownList and Label code is:

    <asp:CommandField ShowEditButton="True"  ButtonType=Button />
                <asp:TemplateField HeaderText="AccountID" SortExpression="AccountID">
                    <EditItemTemplate>
                        &nbsp;<asp:DropDownList ID="cboBrokerAccount" runat="server" DataSourceID="dscBrokerAccount"
                            DataTextField="AccountID" DataValueField="AccountKey" SelectedValue='<%# Bind("AccountID", "{0}") %>'
                            Width="138px">
                        </asp:DropDownList>&nbsp;
                    </EditItemTemplate>
                    <ItemTemplate>
                        <asp:Label ID="lblBrokerAccount" runat="server" Text='<%# Bind("AccountID") %>' Width="80px"></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
 
There is a StartDetails button that refreshes and rebuilds the gridview.

   Protected Sub btnStartDetails_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnStartDetails.Click

        'Build new rows in the purchases maintenance grid  
        Dim strConnection As String = "Data Source=BURCEL05;Initial Catalog=StockSelectSQL;" _
& "Integrated Security=SSPI"

        Dim conStockSelector As SqlConnection
        conStockSelector = New SqlConnection(strConnection)
        conStockSelector.Open()

        Dim strInsertSQL As String = ""
        'Make sure symbolname and purchase date entered
        'Get the SymbolID
        Dim strParam As String = ""
        Dim intRows As Integer = 0

        Dim intSymbolID As Integer = GetSymbolID(txtSymbolName.Text, conStockSelector)
        txtSymbolID.Text = intSymbolID
        Dim strSecName As String = GetSecName(intSymbolID, conStockSelector)
        txtSecName.Text = strSecName
        Dim strUserId As String = Membership.GetUser(User.Identity.Name).ProviderUserKey.ToString()
        Me.dscPurchases.SelectCommand = _
        "SELECT Pur.SymbolID, Acc.AccountID , Pur.BrokerAccountKey,Pur.BuyQty, " _
        & "CAST(Pur.BuyPrice AS Decimal(5,2)) As BuyPrice, " _
        & "Pur.UserID, CONVERT(VARCHAR,(Pur.BuyDate),1) As BuyDate, " _
        & "CAST(Pur.BuyComm AS Decimal(5,2))As BuyComm, Pur.BuyCompleted, Pur.BuyTransID " _
        & "FROM Purchases As Pur " _
        & "INNER JOIN Account as Acc ON Pur.BrokerAccountKey = Acc.AccountKey " _
        & "WHERE (Pur.UserID = @UserID) AND Pur.SymbolID=@SymbolID " _
        & "AND Pur.BuyDate=@BuyDate"

        strInsertSQL = "INSERT INTO dbo.Purchases " _
        & "(UserID,BuyDate,BuyCompleted,SymbolID,BuyQty,BuyPrice,BuyComm,BrokerAccountKey ) "

        strParam = "VALUES ( '" & strUserId & "','" & calBuyDate.SelectedDate & "'," _
        & "0," & intSymbolID & ",0,0,0,1)"
        dscPurchases.InsertCommand = strInsertSQL & strParam
        For intRows = 1 To txtRowCount.Text
            dscPurchases.Insert()
        Next intRows

        'Set source for grid

        dscPurchases.DataBind()
        'grdPurchases.DataBind()
        txtRowCount.Focus()

        grdPurchases.Visible = True

        conStockSelector.Close()
    End Sub

I have been working on this issue for 5 days and am now completely confused.

Can anyone figure out why my code does not work?
Thanks,