WordPress MU

Apologies in advance for asking what may be a stupid question but does WPMU by default ping Ping-O-Matic with each new post for everyone's blog? I notice in execute-pings.php that this line execute_all_pings(); is commented out.

On a possibly related note register_shutdown_function('do_trackbacks', $post_ID); is commented out in wp-includes/functions-post.php does this mean trackbacks are not being done?

Well all my posts were reaching Technorati when I was blogging about Hurricane Rita at http://rita.911blogs.com so I assume the ping-o-matic stuff was working.

Not sure about the trackbacks though.

Unfortunately on my installation trackback doesn't seem to be working. I will be happy if anyone can prove me wrong though.

Nop, obviously my network proxy block the execute-pings.php command to be called from an iframe without me knowing it.

Bypassing the proxy successfully execute the script without problem.

Hum.
My posts are going to technorati alright. But trackback post to another member blog doesn't show up. I checked SK2 and it's not caught as spam.

Strange. Works on my site when I do a trackback to the same site.

Every trackback, or only a certain post? I find that if users Save rather than Publish with a correct trackback it tends not to get through when the finally Publish. Also publishing first to a dead end trackback(ex. typo) then correcting it doesn't always work either.

Copy/paste to a new post with a new trackback has always been the cure for a stubborn trackback.

I call this "burping" the trackback.

I wish there was an admin button to clear the trackback field from the database in these cases. But the "human spam" could be huge.

I have not seen a case where all posts never trackback, unless they simply are not entering the correct trackback url.

I'm now testing trackback in to different posts of different blogs. No luck so far.. Checked the setting and made sure that trackbacks are allowed. I also removed SK2 to make sure that SK2 is the the source of the issue..

Update:
I tested trackback from my blog to another site and it shows up nicely. Therefore I'm have more confident on the assumption that it is the receiving end of trackback that is having problem.

Can I get a hand on this topic?