Trouble Posting Comments?

I tired to post a comment to a blog and it said only members could post comments. I'm not exactly sure what that means, I had no issues posting comments last week, and was able to post a comment a couple of days ago. If anyone knows what I can do to fix my issue, let me know!

Thanks!!

Test Post

Hi everyone! Here's my test post finally.
I am really looking forward to working with you all this semester.