[kxs]

you need a certain karma level to be able to downvote

edit: it used to be 100, I dont know if its still the current threshold

[b-e-p]

Ah, ok thanks. Is there a way I can see unread replies to my comments without having to manually go to all the comments I've seen?

[what]

Threads link in the header shows you all the comments you have made and replies to them.

[b-e-p]

Thanks.

[johnfn]

I just got downvoting at around 200 karma.

[Ardit20]

I think it is more complicated than that. I see for example posters I can down vote and other posters I can not.

[petercooper]

This probably isn't the full picture, but you can't vote down comments left directly in response to your own comments (for obvious reasons), nor can you vote down comments over a certain age or that are already of a very low score.