Migration from Joomla 1.5 to 2.5

Anson,
What you describe will likely run into some issues since you're on v4.2.5 of JFBConnect. I'd recommend the following:
* Install v4.3.x (available in the download area) on Joomla 1.5. That will upgrade your tables to the 4.3/5.0 release
* Install v5.0.1 on your Joomla 2.5 site.
* Run SP Upgrade
* Copy all of the following tables from the 1.5 to the 2.5 site:
#__jfbconnect_xyz
#__opengraph_xyz
There are multiple jfbconnect and opengraph tables that need to be copied, not just one. I can post them if you'd like, but you should be able to see them easily.

I hope that helps, but if you run into any issues or have questions, just let us know.

Thanks,
Alex