Quando estou efectuando uma nova venda (no caso de este software que estou desenvolvendo), toda vez que adiciono novos items no datagridview ele apareçe juntamente com items(ou vendas) adicionados anteriormente. Gostaria de limpar o datagridview antes de adicionar novos items(ou efectuar nova venda).

Estou usando o codigo abaixo, porém não está resultando.

Private Sub lvTable_ItemChecked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ItemCheckedEventArgs) Handles lvTable.ItemChecked     Try          If lvTable.CheckedItems.Count > 0 Then             Dim Condition As String = ""             Dim Condition1 As String = ""             For I = 0 To lvTable.CheckedItems.Count - 1                  Condition += String.Format("'{0}',", lvTable.CheckedItems(I).Text)                 Condition1 += String.Format("'{0}',", lvTable.CheckedItems(I).SubItems(1).Text)             Next             Condition = Condition.Substring(0, Condition.Length - 1)             Condition1 = Condition1.Substring(0, Condition1.Length - 1)             DataGridView2.Visible = True             con = New OleDbConnection(cs)             con.Open()             Dim OleDb As String = "Select Item_ID,DishName, SUM(Qty), KOTGenerationItems.Rate, SUM(Amount), DiscPer, SUM(Disc), VATPer, SUM(VATAmt), STPer, SUM(STAmt), SCPer, SUM(SCAmt), SUM(TotalAmt),TableNo,GroupName from KOTGeneration,KOTGenerationItems,Dish where KOTGeneration.TicketID=KOTGenerationItems.Ticket_ID and KOTGenerationItems.Item_ID=Dish.ItemID and TableNo in (" & Condition & ") and GroupName in (" & Condition1 & ")   group by Item_ID,DishName,KOTGenerationItems.Rate,DiscPer,VATPer,STPer,SCPer,TableNo,GroupName order by TableNo"             cmd = New OleDbCommand(OleDb, con)             rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection)             DataGridView2.Rows.Clear()             While (rdr.Read() = True)                 DataGridView2.Rows.Add(rdr(0), rdr(1), rdr(2), rdr(3), rdr(4), rdr(5), rdr(6), rdr(7), rdr(8), rdr(9), rdr(10), rdr(11), rdr(12), rdr(13), rdr(14), rdr(15))             End While             con.Close()             txtCash.Text = "0.00"             TotalCalc1()             Calc()         Else             Clear()             DataGridView2.Rows.Clear()             DataGridView2.Visible = False         End If     Catch ex As Exception         MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)     End Try End Sub