Posting comments

I have had several people contact me saying that their comments were not posted. I believe I have everything checked as per the suggestions, and can add comments myself under the blog admin name as you can see on the sample post below. What am I doing wrong?

Here is a sample post where I have added a comment.

Here are my settings: Have checked the following Default article settings
Attempt to notify any blogs linked to from the article
Allow link notifications from other blogs (pingbacks and trackbacks)
Allow people to post comments on new articles

Author does not have to put email address in there.

Is there anything else that I should be doing?