domain is correct. It says edc.lan
when I check other Pc its like this judith@edc.lan. On other pc's the network works fine with that.

Rather than trying to join the domain EDC.LAN, have you tried joining the domain EDC instead?

Are you able ping the server from a Command Prompt on the PC?

Is the problem PC running the same operating system as the PCs that work OK?

I have tried it with EDC only. And also it runs the same operating system as the other computers.