As Wod & Jaba said, it is simply a shortage of B744's. Problem originally started with the 2 year delay in A380 (aka Dugong) deliveries, which meant that heavy maintenance on the B744s was deferred to keep the services operating. Once all flexibility in deferring maintenance had been exhausted the aircraft had to be sequenced through HM - this was made worse by an AD from Boeing which required additional work during the "D" checks which added 11 days to the time that each aircraft is out of revenue service. Then you add the Oxy bottle explosion which took OJK out of service for 4 months in Manila and when it was about to return to revenue service, it was involved in the towing incident at Avalon - the other aircraft involved in that incident (OJM) has now been repaired & is back in service.
There are two more Dugongs scheduled to join the fleet before the end of the year so they should release enough B744 capacity to start doing the AKL-LAX-AKL route again. There is also a plan to reduce services because of the economic downturn so we will shortly have a surplus of capacity on the B744.