datagridviewcomboboxcell value invalid exception

See more:

VB

how to set the displaymember & valuemember for a combobox cell which datasource is a list of custom type and every cell content differs from row to row ??



my code is :

Public Class QtyObject
        Public Property Qty As Integer
        Public Property expdate As Date
        Public Property Dis As Integer
        Public Property DType As JomlaItem.JType
        Public Property Client As Client
        Public Overrides Function ToString() As String
            Return Qty.ToString & " | " & expdate.ToString("dd/MM/yyyy")
        End Function
    End Class
Private Sub TextBoxSales_TextChanged(ByVal sender As Object, ByVal e As EventArgs)

        Try
            
            Dim qtties As New List(Of QtyObject)
            Dim b = From r As DataRow In ds.tblItems.Rows
                  Where r.Item(1).ToString = str
                  Select price = CDbl(r.Item(2)), code = CInt(r.Item(0))


            If b.Count > 0 Then
                dgvSales.CurrentRow.Cells(1).Value = b(0).price
                x = b(0).code

                Dim d = From r As DataRow In ds.tblEXPData.Rows
                        Where CInt(r.Item(1)) = x
                        Select quantity = CInt(r.Item(2)), expdate = CDate(r.Item(3))
                        Order By expdate

                If d.Count > 0 Then
                    For i = 0 To d.Count - 1
                        
                        Dim q As New QtyObject
                        q.Qty = d(i).quantity
                        q.expdate = d(i).expdate
                        qtties.Add(q)
                    Next
                    With DirectCast(dgvSales.CurrentRow.Cells(2), DataGridViewComboBoxCell)
                        .DataSource = qtties
                        
                    End With
                    
                Else
                    DirectCast(dgvSales.CurrentRow.Cells(2), DataGridViewComboBoxCell).DataSource = Nothing
                End If
            End If
        Catch ex As Exception

        End Try
    End Sub

i asked the question this way because i searched google and the similar problems were answered that the problem is in setting the displaymember and the valuemember,

the combobox cell is populated with data without problems, the exception is thrown when it loses focus the exact exception message is : The following exception occurred in the datagridview : System.argumentException :datagridviewcomboboxcell value is not valid To replace this default dialog please handle the dataerror event.

if the problem that caues the error message (datagridviewcomboboxcell value invalid exception) is elsewhere ,please kindly help me solving it,
Thanks alot.