Report: workstation and WS Requester and WS Department

Dear ServiceDesk
(ServiceDesk 6012)
I need a report (asap) that contains workstation and WS Requester sorted WS Department.
I want to see all the installation dates from a certain date, (for that purpose I also created an additional field: Installation date).

The reports I made didn't give all the results: I assigned the workstations in the inventory to a user. But when I want to see also the department of that user the message appears: not assigned!!!

Is it a bug?
Can you create a query for me?
Isn't it possible for ServiceDesk to take the date the workstation was created?

Please see the attached jpeg for an example.

Thanks in advance

F. Pranger