oslc query new Attribute

I'm trying to use OSLC query.
https://localhost:9443/jazz/oslc/contexts/_WSmpcIgJEd-Vr42ll5AhIQ/workitems?oslc_cm.query=dc:identifier%3D"476"

it shows work item (476) values. But we added new attribute the work item.
Work item's new attributes doesn't be listed. How can i list work item's values and new attribute values. Should I change the query or ..?
and also I try

https://localhost:9443/jazz/oslc/contexts/_WSmpcIgJEd-Vr42ll5AhIQ/workitems?oslc_cm.query=dc:identifier%3D%22476%22&oslc_cm.properties=dc:title,dc:identifier,dc:test

It lists identifier and title values,but doesn't list test(new Attribute).

Regards.