คำสั่ง SQL มันผิด ตรงUnitsinStock บวก สต็อกเพิ่ม ช่วยหน่อยครับผมแก้ล่ะก้ยังเหมือนเดิม T T

Private Sub Too_Save_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Too_Save.Click
        '---บันทึกตาราง PurchaseOrder
        Dim sb As StringBuilder
        If TxPOID.Text.Trim() = "" Then
            MessageBox.Show("กรุณากดปุ่มเพิ่มใบสั่งซื้อก่อน", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
            Exit Sub
        End If

        If MessageBox.Show("คุณต้องการเพิ่มใบสั่งซื้อหรือไม่", "", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.No Then
            Exit Sub
        End If


        Dim SqlS As String = ""
        sb = New StringBuilder()
        sb.Remove(0, sb.Length)
        sb.Append("INSERT INTO PurchaseOrder(PurchaseOrderID,PurchaseOrderData,ReceiveData,Status,SupplierID)")
        sb.Append("VALUES(@poid,@podate,@re,@st,@supid)")
        SqlS = sb.ToString()

        With cm
            .Parameters.Clear()
            .CommandText = SqlS
            .Connection = cn
            cn.Open()
            .Parameters.Add("@poid", SqlDbType.NVarChar, 5).Value = TxPOID.Text
            .Parameters.Add("@podate", SqlDbType.DateTime).Value = Date_OrderData.Text
            .Parameters.Add("@re", SqlDbType.DateTime).Value = Date_ReceiveData.Text
            If RD_Pro.Checked = True Then
                .Parameters.Add("@st", SqlDbType.NVarChar, 1).Value = "0"
            Else
                .Parameters.Add("@st", SqlDbType.NVarChar, 1).Value = "1"
            End If
            .Parameters.AddWithValue("@supid", CStr(CB_Supplier.SelectedValue))
            .ExecuteNonQuery()
        End With



        '---บันทึกตาราง PurchaseOrderDetail
        Dim i As Integer = 0
        For i = 0 To ListView1.Items.Count - 1
            sb.Remove(0, sb.Length)
            sb.Append("INSERT INTO PurchaseOrderDetail(PurchaseOrderID,NumberToOrder,Price,Total,ProductID,Netvat,Sumtotal)")
            sb.Append("VALUES(@poid,@num,@pri,@tot,@pro,@net,@sum)")
            SqlS = sb.ToString()

            With cm
                .Parameters.Clear()
                .CommandText = SqlS
                .Parameters.Add("@poid", SqlDbType.NVarChar, 5).Value = TxPOID.Text
                .Parameters.AddWithValue("@num", CInt(ListView1.Items(i).SubItems(4).Text))
                .Parameters.AddWithValue("@pri", CSng(ListView1.Items(i).SubItems(3).Text))
                .Parameters.Add("@tot", SqlDbType.Float).Value = CSng(ListView1.Items(i).SubItems(5).Text)
                .Parameters.AddWithValue("@pro", ListView1.Items(i).SubItems(1).Text)
                .Parameters.Add("@net", SqlDbType.Float).Value = TxVat.Text
                .Parameters.Add("@sum", SqlDbType.Float).Value = TxSUM.Text
                .ExecuteNonQuery()
            End With



            '---บวกเพิ่มสต็อก


            sb.Remove(0, sb.Length())
            sb.Append("UPDATE Products")
            sb.Append("SET UnitsinStock =@un")
            sb.Append("WHERE (productid=@proid)")

            Dim sqlupate As String
            sqlupate = sb.ToString

            With cm
                .Parameters.Clear()
                .CommandText = sqlupate
                .Parameters.AddWithValue("@un", CInt(ListView1.Items(i).SubItems(6).Text))
                .Parameters.AddWithValue("@proid", ListView1.Items(i).SubItems(1).Text)
                .ExecuteNonQuery()  
            End With
        Next
        MessageBox.Show("บันทึกข้อมูลเรียบร้อยแล้ว")


    End Sub