Nicodemuus

Was just wondering if anyone could help me with my problem. I have made a custom mob, and while running minecraft through eclipse the mob works great, spawns like it is supposed to and also am able to use the spawn egg. However when i reobf and zip up the source and throw it in my normal minecraft mods folder and try to spawn it with the egg the game crashes with this error... Also I am using the newest direwolf20 modpack. If you need any more info just ask.