Windows Authentication not working on server

[roota]

I'm developing a website in asp.net and C#.I've created the website so when a user goes to the site, his windows client username is read out with: System.Security.Principal.WindowsIdentity.GetCurrent().Name.ToString(); and then I lookup his username in the db and create a user object with all necessary data (team, name, permission level, role, ...)from the return data. Then I keep this object in a session var until the user logs out.This was working like a charm locally but know I've deployed to the server I get defaultAppPool for every user.What am I doing wrong?In my web.config file I have:authentication mode="Windows"I have to admit this is the first time that I'm doing the deploying myself and everything went smoothly except for this.