By "comments" do you mean blog comments? You may need to wait around for approval as most sites moderate incoming comments before the comments are posted. Or, if the owner is really stingy, the person will remove links from the post, should there be any prior to approval. :naughty:
I guess your website/ip has been blacklisted by akismet.
Do a quick Google search and find some blogs where you can test if the akismet filter sorts out your comment.