Tridion Core Service Reference becomes unknown after I 'Update' the service reference in VS 2010 -

Tridion Core Service Reference becomes unknown after I 'Update' the service reference in VS 2010 -

i using tridion core service in project(vs 2010 .net framework 4.0)

when update service reference become unknown. removing references after updating tridion core service reference.

can 1 suggest me missing?

starting sdl tridion 2011 sp1, tridion started shipping pre-built coreservice client. can find dll under [tridion]\bin\client\tridion.contentmanager.coreservice.client.dll.

other usual classes, includes optimizations done client. details on how utilize assembly available in tridion practice.

tridion tridion-2011 tridion-core-services