Sorry - I wanted to get the subject line for this question right...
I had a nasty time upgrading from MT 4.0 to 4.21 and ended up deleting all of my plugins and normal MT directories (i.e. extlib, tools, mt-static, lib, etc, etc) and copying the files for 4.21 back to the system. The mt-upgrade process finally went smoothly. I went back to try to install the plugins I originally was using - AS 1.0 being one of them.
Well, AS 1.0 and 1.1 aren't working and without any error reporting that I can see, I can't figure out why.
I followed Mark's recommendation at http://forums.movabletype.org/2008/08/does-actionstreams-10-work-wit.html where I incremented the schemaversion (was 9 and changed to 10) in config.yaml in plugins/ActionStreams and re-ran mt-upgrade.cgi. The output claimed changes were being made and things were being upgraded (I *wish* I had written down what the output was), but AS is still not working.
I then went further and modified the mtplugindata and mt_config tables and removed any mention of AS. When I went back to the mt.cgi to check user info, etc, the system prompted me to upgrade to support AS 1.1. This time, I would have written down information, but it simply reported that the upgrade went fine.
I have disabled and re-enabled the plugin, deleted other profiles and re-added them, run 'run-periodic-tasks' by hand to no avail. There aren't any errors in the Activity log nor my system logs. So, at this point, I'm lost...
Any ideas out there?
Reported on Movable Type 4.2

Ok... so what I did above did work. It took an hour to show up in the Action Streams list under my user profile. Thing is that nothing showed up in the activity logs, nor errors on the CLI when I ran run-periodic-tasks by hand. I wish there were a way to up the verbosity of any logging by AS. Wonderful tool, when it works.