It is difficult to get reliable information in Myanmar about travel and general Myanmar info! The good side of knowing Myanmar info is that it gives you a flexibility to decide how you make decision to travel Myanmar. Sometimes you will have wrong information from
Myanmar travel and tour (MTT). They said you have to have permission to travel Dawae and cross Myanmar border from Myeik to Thailand. Actually you don't need anything you can just visit there and cross border to Thailand. So information you are getting from travel agent is incorrect. It is a claim that should be accepted by everyone. Even to get the travel permit it takes one to two weeks processing day to get and you are not sure about whether you get it or not. The bad side of this is that it often takes months for a new authorization issued by Yangon to reach the concerned area.