Does anyone know why I can book SAN-SIN in business class through the SQ website(http://www.singaporeair.com/saa/en_UK/index.jsp), but not SAN-HKG?

Perhaps for some reason they feel that they lose revenue if they don't make the booking all the way to SIN is my guess, or they are in the process of making that option available.

Appreciate any insightful comments.

Regards
LH