Ryan,
We don't check any of your Canvas settings before allowing you to send Requests, so that should be the problem at all.. it's also something I realize we should add in future releases as a check before people start sending them
The reasons for failures (something we need to document better) are:
1) The user has de-authorized your application. Obviously, this is unlikely if you're sending it to yourself.
2) Your Migration settings (in the Advanced section of your Facebook Application) aren't set up properly. Please make sure the following set:
Requests 2.0 Efficient: Enabled
Upgrade to Requests 2.0: Enabled
3) If you need to make changes to the settings above, please log out of the admin area before you try to send again. We have a safety check in JFBConnect that if a request is being sent that you can't mess with some of the settings within JFBConnect.. if the sending fails, like you mention, it may trigger that failsafe and not let you send more Requests until you re-log in (clearing the session).
Definitely test by sending to yourself first, before sending to all users. That way you can test that you received it and that the Accept (within Facebook) loads the right page.
I'll be on the site this weekend to do more testing. We're trying to recreate your IE issues on our development server to not do many code changes on a 'live' site, something we never like doing. Your recent post about your debugging has helped us a bit, but still no definitive answers. When I'm on your site, I'll try to send a request to myself and see if I can narrow down possible issues. We sent thousands of requests yesterday without issue, but we're on Joomla 1.5 here.. Joomla 1.7 was tested thoroughly for requests (where we developed the feature actually), but possible there's some conflict we didn't expect.
Thanks,
Alex