Ssas cannot connect to the redirector

Hi,
I run Sql express 2014 with data tools. I build an analysis project with visual studio 2015 community. I create a data source and view without problems, i can see the data's from my SQL database. But when i build a dimension and try to process it i got this message: Cannot connect to the server. Verify the name of the server or that Sql browser is running. The sql browser is running, i tried with different services accounts. I desactivated any AV to test if a firewall was blocking the 2382 or 2383 port. I can see the source data in the view. I used several accounts having full sql access.
Can somebody help please
Thank you
John