MapleStory v83 Crashes When Selecting a Character

Hello everyone. I'm currently writing a private server from scratch using HeavenMS as a reference, since it would be fun to give it a try and learn new things along the way. Right now, I just can't seem to get past the character selection screen, in order to get into the world. The game just crashes without giving any error at all. So, I have no clue how to debug it. I have spent hours trying to figure it out, but I don't know what is wrong with it. Can anyone help me please? Here is the source and the video that shows what I'm talking about: dead link - - - Updated - - - I forgot to mention, I'm thinking it could that I send the wrong packet? I'm not sure... It's located in client->packets->SetField.java