Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
        Dim startnummer As String = txtStartnummer.Text
        Dim vorhanden As Boolean
 
        Me.BindingContext(dv_stand).SuspendBinding()
        dv_stand.Sort = String.Empty
        For Each drv As DataRowView In dv_stand
            If drv("STNR") = startnummer Then
                drv("RDN") += 1
                drv("ZEIT") = Now
                vorhanden = True
            End If
        Next
 
        If Not vorhanden Then
            Dim drv As DataRowView
            drv = dv_stand.AddNew()
            drv("ZEIT") = Now
            drv("STNR") = startnummer
            drv("RDN") = CInt(1)
            drv.EndEdit()
        End If
 
        CType(Me.BindingContext(dv_stand), CurrencyManager).Refresh()
 
        dv_stand.Sort = "RDN Desc, TIMER Asc"
 
End Sub