In land_data.narc the length of the second block is supposed to be multiple of 0x30. This is true for all maps except for nr 483 (m_dun2405_00_01c). It has the lenght 146(0x92) instead of 144(0x90). That means there are 3 buildings and two additional bytes (0x0d 0x0a)
Why?!
(I use the Pokemon Diamond ROM)