Error Pinging Blog

[Stickup Artist]

My feed subscribers went from over 100 down to 15 overnight.

Tried pinging and got the following error:

Your Ping resulted in an Error "We were unable to process your ping. You must ping with a URL that exactly matches the channel link (RSS) or alternate link (Atom) in your top level feed element pointing back to your website (e.g http://myblog.blogspot.com/), or use your feed URL (e.g. http://feeds.feedburner.com/myuri)."

I tried pinging:

http://stickupartist.blogspot.com/

and

http://feeds.feedburner.com/blogspot/lPzKB

I've pinged many times before and was successful. Am I doing something wrong this time, or is something broken?

Thanks in advance for any help!