Show Reference list item

Hello Everyone,

I'm not really good in Calculation right now, so I neel your help for something probably really simple.

In my Incident Window, I select the User (known as Raise User in this Window), and when selecting the user, we want to see some informations from that user, like phone number, job title, etc. So far so good. The problem is when I want to see some information from a reference list, like the department. So, I did create a new attribute from the user business objects called "DepartmentShow", selected Calculation type after read and tried this calculation:

import System 

static def GetAttributeValue(System): 

          Value = System.Department.Title 

          return System.GetNamedObject("System.User", Value)

I tried few changes in this calculation, but nothing worked so far. Maybe your guys can help me!

Thank you