VB.NET(2003) SQL Parameter

Private Function QueryOrder(ByVal strOrder As String, ByVal oleCon As OleDb.OleDbConnection) As Boolean
Dim ds As DataSet
Dim dataCount As Integer
Dim da As OleDb.OleDbDataAdapter
Dim cmd As OleDb.OleDbCommand
Try
ds = New DataSet
Dim strSql As String = "SELECT CustomerCode as CstCode,PartNo As PN,ConfirmDelDate As DueDate,Cast((Qty*1000) as integer) As SumQty," & _
"Cast((ShippedQty*1000) As Integer) As ShippedQty,ShipQty='',NonConvCOID As ID,COIDLevel,Status From tbl_backlog " & _
"Where OrderNo= ? " & _
"And NonConvCOID Like 'FZ%TA' " & _
"And Undone='FALSE' Order by ConfirmDelDate ASC"

If oleCon.State = ConnectionState.Closed Or oleCon.State = ConnectionState.Broken Then
oleCon.Open()
End If
cmd = oOleDBC.CreateCommand()
cmd.CommandType = CommandType.Text
cmd.CommandText = strSql
cmd.Connection = oleCon
da = New OleDb.OleDbDataAdapter(cmd)
da.SelectCommand.Parameters.Add("@OrderNo", OleDb.OleDbType.VarChar, 30).Value = strOrder
dataCount = da.Fill(ds, "OrderInfo")
If dataCount = 0 Then
PopMsg("Warning", "Can not find data!", MsgBoxStyle.Critical, "OrderNo:" & strOrder)
Return False
End If
For n As Integer = ds.Tables("OrderInfo").Rows.Count - 1 To 0 Step -1
If ds.Tables("OrderInfo").Rows(n)("Status").ToString = "Shipped" Then
ds.Tables("OrderInfo").Rows(n).Delete()
End If
Next
ds.Tables("OrderInfo").AcceptChanges()

If ds.Tables("OrderInfo").Rows.Count = 0 Then
PopMsg("Warning", "The Order has been shipped!", MsgBoxStyle.Critical, "OrderNo:" & strOrder)
Return False
End If
BuildListViewFromTable(lvOI, False, "OrderInfo", ds)
For i As Integer = 0 To lvOI.Columns.Count - 1
If lvOI.Columns(i).Text = "ID" Then lvOI.Columns(i).Width = 0
If lvOI.Columns(i).Text = "COIDLevel" Then lvOI.Columns(i).Width = 0
If lvOI.Columns(i).Text = "Status" Then lvOI.Columns(i).Width = 0
Next
Return True
Catch ex As Exception
Return False
Finally
cmd.Dispose()
da.Dispose()
cmd = Nothing
da = Nothing
oleCon.Close()
End Try
End Function