Ping not posting to all status update sites (or to Twitter at all)

I've sent two status updates over the past couple days. The first went through to Facebook, Twitter and Myspace. Great. Sent a second thought that only got through to Facebook. So I resent it directly to Myspace, which went through, and tried to do so with Twitter, but the Twitter one didn't post at all, nor does it show in my recently sent posts on ping.

Does ping work consistently for most of you? I'm having more problems that success. FYI, I resynched all of my accounts before trying to send the above pings, so that's not the issue.