Trackbacks and Pingbacks

I'm finding that trackbacks and pingbacks are not working reliably with my main blog or any of the hosted blog accounts. Of course, I would prefer that pingbacks just work since they are supposed to be effortless.

I have "Allow pings" checked on every post and page and "Allow comments" on the majority.

I don't know if it matters, but I have XML-RPC enabled on some blogs to allow software updates, but it doesn't seem to make a difference to pingbacks.

I usually get a pingback if I link between articles in the same blog. I'm puzzled. For example, http://bestagentblogs.com/twitter-in-plain-english-video/ shows the pingback from http://bestagentblogs.com/blogs-in-plain-english-video/ (I deleted most pingbacks among these pages, but left this one as an example.)

I created this page to test:
http://bestagentblogs.com/trackback-pingback-test/

Update: Nothing appears in the "Discussion" section of the initiating blog to indicate that a ping was sent anywhere.