Changing the server option in the control panel does not change the server it just chooses a different server.jar. Because modded servers such as Feed the Beast, Technic Launcher, ATLauncher, VoidsWrath servers have different mod files per install you need to change all the files on your server.
We can Install/Upgrade The Server
If you are unsure how to change your server, we can change the server for you, we offer unlimited re-installs and upgrades on all servers. Just complete this form to upgrade or reinstall : https://stickypiston.co/account/submitticket.php?step=2&deptid=7