Can't Load World in Custom Modpack!?

[saddlepiggy]

Hello community, I am having trouble loading worlds in my modpack. Whenever it tries to load or create a world, just as its about to load (I think), it crashes.Heres the report: http://pastebin.com/5tcXziW1   Thanks, saddlepiggy!

[FCPWiz]

You have a duplicate ID in your modpack. Go to the WeaponMod config found in the /config/ folder. In the file, find ID 27 and change it to something else. Then try loading a world again.

[Nentify]

You have a duplicate ID in your modpack. Go to the WeaponMod config found in the /config/ folder. In the file, find ID 27 and change it to something else. Then try loading a world again.

​Duplicate ID of what? It looks like some sort of entity ID conflict or something, but I'm not so sure. But be worth contacting the mod developer.