Why can I not comment on an OP?

This is my fourth time of posting this question. I keep falling foul of the 72 hour rule. I've now been a member for 11 days so my original ask must be five days ago. My question could be a stupid one but I am never offered the option of responding to the OP. I can respond to the comments.

In addition and not related to the above, after 11 days I've gone from 2 Karma to 0. I think I have acquired an enemy on one of the sub Reddits. I do have upvotes, I think. Some of my comments have red arrows (upvotes?), including one which has the number 3 next to it. None of these affect my profile, whereas downvotes seem to have an immediate effect