I have a combo box control inside a data grid view so I have to have code to be able to enter a custom value. But my code doesn't work, the code works fine if the user types in a custom value but doesn't work if it is one of the values from the combo box list. Here is a copy of my code that performs the task. In both cases the variable strValue contains the value that we are looking for but when the program exits from the sub the value is removed if it was selected from the list. Does anyone have any ideas on how to fix this?

    Private Sub dgdRevisions_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles dgdRevisions.CellValidating

        'These lines allow the user to type their own values into the datagridview comboboxes

        If e.ColumnIndex = colDescriptionLine1.DisplayIndex Then

            Dim combobox As DataGridViewComboBoxCell = dgdRevisions(e.ColumnIndex, e.RowIndex)

            'Store e.FormattedValue in Variable

            Dim strValue As String = e.FormattedValue.ToString.ToUpper

            'Clear text

            dgdRevisions(e.ColumnIndex, e.RowIndex).Value = ""

            'Clear existing Items in combobox

            combobox.Items.Clear()

            'Add default Items to combobox

            PopulateStandardDescriptions(e.ColumnIndex, e.RowIndex)

            'Add user value to combobox

            If Not combobox.Items.Contains(strValue) Then

                If Not strValue = "" Then

                    combobox.Items.Add(strValue)

                End If

            End If

            dgdRevisions(e.ColumnIndex, e.RowIndex).Value = strValue

        End If

    End Sub