Yeah, right now it's....
Current Overall Rank: #162
Current Category Rank: #31
So I am not sure what that was. Temp glitch is all I can suggest because you've had steady traffic over the last month and I didn't do anything to your account.
You'll generally not be ranked for two reasons:
A) you took the voting banner off your site or changed domain names and so haven't sent in a referral for 30 days from your registered domain
B) you're account has been suspended or removed.
I rarely remove ranked accounts. If they are ranked then there is still activity on the blog. I am not to quick to remove accounts because sometimes bloggers just take a break. But if an account has been inactive/un-ranked for a long time, it is more likely to be removed during a manual review.
Accounts are usually suspended for asking for clicks/votes in a giveaway entry. As soon as the blogger removes the TMB link from giveaways, they're back up.