Originally posted by [b]skyleo[/b]
http://www.eathena.ws/board/index.php?autocom=bugtracker&showbug=4676
Mercenaries don't teleport to their master when a player moves more than 15 tiles away from them.
Source:
http://irowiki.org/wiki/Mercenariesat: Mercenary Details under Separation:
If a mercenary moves more than 15 cells away it will be teleported to the summoner's position.