I got excellent for mine and posted 3-4 times a week.
I would seriously contact your forum supervisor and ask what you did wrong (edit: if it was even anything at all).
This is what I sent the coordinator of the blogs: "I posted on the blog every day, sometimes twice a day. I also read the blog every day. I properly referenced everything that needed to be referenced. I also made sure to answer all the other student's questions in the blog and work with them, and not just post mindlessly. I really made conscious contribute a lot so that I could get an "EX".
It is annoying, because being really honest, I actually tried really hard hahaha...hopefully they can at least give me some feedback, if not change my mark
