Why Cant up fishing job for later lv75

[wikipedia]

fishing have lv75 .
so NPC of Helternt village(106,324) tall me to kill 20 orc.
but i have kill 20 orc reture NPC.
Yet NPC say "Kill 20 of those Orcs please" .
can't up fishing lv75 to more.
Is it a BUG ,right?