Found the value of a combobox in datagridview

Private Sub dataGridView1_CellValidating(ByVal sender As Object, ByVal e As DataGridViewCellValidatingEventArgs) Handles Movement_roller_DDataGridView.CellValidating

    Dim headerText As String = _
        Movement_roller_DDataGridView.Columns(e.ColumnIndex).HeaderText

    ' Abort validation if cell is not in the CompanyName column.
    If Not headerText.Equals("Κωδικος Roller") Then Return

    ' Confirm that the cell is not empty.
    If (String.IsNullOrEmpty(e.FormattedValue.ToString())) Then
        Movement_roller_DDataGridView.Rows(e.RowIndex).ErrorText = "Ο Κωδικώς Roller δεν μπορεί να είναι κενός"
        e.Cancel = True
    End If
End Sub