File does not exist (com_jfbconnect_j1.5_v3.1.2)

That's very strange. We've never seen that before, and 3.1.2 has been installed hundreds of times.

My best suggestion is to try unzipping the whole component to a directory on your server (like /var/www/html/joomla/tmp) and then using the "Install from Directory" option from the Install/Uninstall screen. Hopefully that will fix the issue, but if it doesn't (and it says a file doesn't exists) you should be able to very quickly verify that the file is indeed there.

Finally, please make sure that you're running Joomla 1.5, and that the /components and /tmp directories are writeable. You can see this if you go to Help->System Info and click the Directory Permissions tab.

If that doesn't help, let us know and we'll see what more we can do.

JFBConnect is not compatible with Joomla 1.6 yet. It's a Joomla 1.5 only component. We're working on the 1.6 compatible version, but it likely will not be ready until late March, at the earliest.

Hope that helps explain your issue, and good luck!