Mists of Pandaria

Hello guys, i have a problem with the quests, when i get a quest to kill something, after i kill it doesn't count as a kill, I mean I kill and kill and kill and still 0 out of 10 for example, and from other quests like kill X to recieve Z, still i don;t get nothing out of my kills... Help please.!

Are you in a raid group? If so, quit it.

Solo / Party / Ride Still the same, i downloaded Mists of Pandaria (old) but now i am trying to download the one without (old)

so you are lvl 1 or 2 since you cant complete quest? Or this problem started suddenlly afterward?

Might be stupid, are you sure you are killing correct npc?

Or quest might be bugged. Maybe tell us the name of the quest.