Need help for SQL query

[sazd1]

I am using vb express and MsAccess as database. I am trying to write a query for the calculation of Stock. My tables are as under: PId PDate ItemId Description Price Quantity Amount 1 28/8/2009 1 Coca Cola Normal 1,00 10 10,00 2 28/8/2009 2 Coca Cola Zero 1,00 5 5,00 3 29/8/2009 1 Coca Cola Normal 1,00 5 5,00 4 29/8/2009 2 Coca Cola Zero 1,00 10 10,00 Data in Sales Table is as under: SId SDate ItemId Description Price Quantity Amount 1 30/8/2009 1 Coca Cola Normal 2,70 2 5,40 2 30/8/2009 2 Coca Cola Zero 2,70 3 7,10 3 31/8/2009 1 Coca Cola Normal 2,70 1 2,70 4 31/8/2009 2 Coca Cola Zero 2,70 2 2,70 I tried something like this to have balance of stock at any date or interval between two dates Dim cmdText As String = "SELECT pt.ItemId, pt.Description, SUM(pt.Quantity)AS QuantityPurchased, SUM(st.Quantity) AS QuantitySold, (SUM(pt.Quantity) - SUM(st.Quantity)) AS Balance FROM PurchaseTable pt INNER JOIN SalesTable st ON pt.ItemId=st.ItemId WHERE pt.PDate Between @START and @END GROUP BY pt.ItemId, pt.Description" If con.State = ConnectionState.Closed Then con.Open() Dim cmd As OleDb.OleDbCommand = New OleDb.OleDbCommand(cmdText, con) cmd.CommandType = CommandType.Text cmd.Parameters.AddWithValue("@START", OleDb.OleDbType.Date).Value = TextBox1.Text cmd.Parameters.AddWithValue("@END", OleDb.OleDbType.Date).Value = TextBox2.Text Dim dr As OleDb.OleDbDataReader If con.State = ConnectionState.Closed Then con.Open() dr = cmd.ExecuteReader If Not dr.HasRows Then MessageBox.Show("No Records Found for Date: " & TextBox1.Text) Else MessageBox.Show("Record found for Date: " & TextBox1.Text) ListView1.Items.Clear() ListView1.ForeColor = Color.DarkRed ListView1.GridLines = True While dr.Read Dim ls As New ListViewItem(dr.Item("ItemId").ToString()) ls.SubItems.Add(dr.Item("Description").ToString()) ls.SubItems.Add(dr.Item("QuantityPurchased").ToStr ing()) ls.SubItems.Add(dr.Item("QuantitySold").ToString() ) ls.SubItems.Add(dr.Item("Balance").ToString()) ListView1.Items.Add(ls) End While End If But i could not get the desired results. Please advise what i am doing wrong with this. Thanks