[RESOLVED] Help Datagridview error: datagridviewcomboboxcell value is not valid?

[coolwater]

I have a datagridview (bound to a DataTable) that has a combobox column (bound to bindingsource). Inserting data is not a problem. The problem occurs when I edit a row the datagridview throws an exception "datagridviewcomboboxcell value is not valid". The DGV combobox turns blank afterwards.

I posted this code to the DGV DataError Event to find the exact error:

        If (e.Context = DataGridViewDataErrorContexts.Commit) Then
            MessageBox.Show("Commit error")
        End If

        If (e.Context = DataGridViewDataErrorContexts.CurrentCellChange) Then
            MessageBox.Show("Cell change")
        End If
        If (e.Context = DataGridViewDataErrorContexts.Parsing) Then
            MessageBox.Show("parsing error")
        End If
        If (e.Context = DataGridViewDataErrorContexts.LeaveControl) Then
            MessageBox.Show("leave control error")
        End If

        If (TypeOf (e.Exception) Is ConstraintException) Then
            Dim view As DataGridView = CType(sender, DataGridView)
            view.Rows(e.RowIndex).ErrorText = "an error"
            view.Rows(e.RowIndex).Cells(e.ColumnIndex).ErrorText = "an error"

            e.ThrowException = False
        End If

I got this error "Error happened formatting, Display" and after I click ok I get this error "Error happened formatting, preferred Size".

I'm stuck. Can't figure out what I am doing wrong?