I also agree. You appear to be running a dolphin 6 site. Upgrading to dolphin 7 while maintaining the mods will not be possible. Best that could be done as prolaznik mentioned would be to migrate the existing users and standard dolphin content.
A facebook connect button is just a image link to the facebook connect module available in dolphin 7. As far as i know there is no facebook connect module for dolphin 6. So unless you have one, the button is of no use.