facebook app doesn't respond to peoples' wall

when someone comments on my wall post or photo, of course the message comes through on my phone, but when i respond through my stock messenger, it sends the person a message to their inbox instead of the wall post or photo comments..

the only way that i know how to respond, is to go the internet website and respond to the post on there, which gets pretty annoying when people keep responding to your posts..

is anybody else having this problem, because i know cheaper phones that can do it