Why can't i reply at some topics in the forum?

Well i just tryed to post my rotation on the monks topic, but then i got this error: New forum post cannot be made due to either you have reached to your daily limit or your main character's level is not high enough.
So i tryed to post somethin in another thread and i'm able to do it there, so what's the point?

lvl restriction of your character or limit of daily exceeded.

can anyone explaim me how this works? becouse as i said i can post on other topics (like i'm doing right now) but not in that one, and i'm lvl 39 so i don't think that's the problem