I can't see my messenger messages on the lockscreen, or drop-down menu. Help?

[xoChelsox]

So.. it's been going on for a few weeks or so I don't remember. But on messenger whenever someone texts me I can see it from the chathead, and I can see "1 chat head opened" or whatever.. but I can't see the messages from the lockscreen or drop-down menu, so I literally have to open my phone just to see if someone from messenger messaged me.

(P.s. I meant to click "Ask A Question" sorry.)