Morton were unable to continue their good start to the season in the Ladbrokes Scottish Championship as they were held to a goalless draw after being reduced to 10 men at home by Dumbarton.Wins over Alloa and Livingston had boosted Morton to fourth in the standings but they struggled to break down a Dumbarton side who had lost their last three games.The hosts dominated possession at Cappielow but drew a blank, losing Conor Pepper to a red card for his second bookable offence in the 67th minute.The stalemate was Morton's second in six league games so far this season.