Styngray

I can load any other mod and i have loaded Tropicraft before but now it gives me this error: The game crashed whilst there was a severe problem during mod loading that has caused the game to fail Error: cpw.mods.fml.common.LoaderException: java.lang.NoClassDefFoundError: modconfig/IConfigCategory I've tried downloading from different site to see if i can get a different version of tropicraft.