Thanks for the information and quick response. As I am new to this, can you tell me why SQ's QMJFKNS does not appear to work?

According to the fare rules, the ticket must be issued in Area 1 (North America) and travelling to Area 2/3, CHECK.
The flight must be transatlantic on SQ 25 or SQ 26. CHECK

Just trying to find the cheapest flight from NYC to BKK between 11/30 and 12/12.

Then, what is the best way to search for these fare classes? Going direct to some of the airlines does not allow you to input the fare class. Any good options for this?

On a separate note, are there any good ways to find cheap mileage runs?

All of the help is appreciated again.