Fanpage username problem

I have been trying to create a custom name for my page pages/Walks-in-Auckland/194524263908119 but FB does not allow me to have a custom name with the word 'auckland' in it. I just don't know where to go to address this problem...

I have already created username for two other pages so I know how easy it can be.

I know I can use any other city name within the username so why is 'auckland'
blocked?

Each Page can have a username
Easily direct someone to your Page by setting a username for it. You will not be able to edit or transfer this username once you set it.
Page Name:
walksinauckland is not available