OLAP Cube process error (A connection could not be made to the data source with the DataSourceID of 'Example_SQL', Name of 'ExampleSQL'.)

Question

I have an Analysis Services Multidimensional Project, I added a data source, data source view, and cube, from dimensions > properties > explore data > I got all data from DB. From cube processing I'm getting the following errors (see attachment):cube procces view

I added "NT SERVICE\MSSQLServerOLAPService" this a login in SQL> Security> logins, set "sysadmin" role