I have a DAP-1522 rev A1 with last firmware available installed, 1.42. I did not replace it when switching over to IPv6 because this D-Link list at the bottom Q&A states it supports IPv6 - http://us.dlink.com/technology/dlink-ipv6-solutions/
I noticed I do not see the IPv6 configuration options in my firmware UI that are shown starting on page 24 here either - http://www.dlink.com/-/media/Consumer_Products/DAP/DAP%201522/Manual/DAP%201522_Manual_EN_US.pdf
Is it possible that only the rev B hardware supports IPv6 and not the A rev? If so, this should be clarified at the D-Link USA support site.