I have an issue: From Jan 2011 to May 2011, I could use my award miles to book for a round flight (standard award) from Austin, TX to Ho Chi Minh City, Vietnam for flying between Jan 2011 to Oct 2011. I could book the award ticket anytime even one day in advance (I did this twice). Since Jun 2011, I notice that if I put in the flight date between Nov 2011 and May 2012 or later for Austin to Ho Chi Minh, the system always throw the error of unavailability. I call 1-800-United-1 and agent still see the unavailability error. Even if I try to book 12 months in advance. Is there something wrong in the system? Or Mileage plus just disallows the booking between Austin and Ho Chi Minh City? I play around with the system since Jan 2011 and start to see this behavior only since June 2011. If I try to book between Austin, TX and Hong Kong it works perfectly even for one day in advance. The error occurs between Hong Kong and Ho Chi Minh City. How should I take this forward? I have like 200k+ of awards mileage and only use them to fly back to Vietnam.