voltz server wont load

[voidcreeper_]

basically i have a singleplayer server which was running the latest voltz modpack and everything was working great then the day 1.5 was released it stopped working and i asumed it was because of the new 1.5 but i re downloaded everything and had reinstalled java and the modpack started working but the problem is when i try to join my world it says building work loading and doesnt do anything but it allows me to make a new and play it.does anyone know what i could do because i spent so much time on my first one.or it could be because im a nub i bought my prem acc 2weeks ago :/