@Manish and @Stefano,
Team, Sector and DailyReserveSector are 'alias' to the {Sector}, so that should not be the problem.
@Jeroen,
Assuming the error is the same as the one in the OP.
Check if your output structure is correct.
It should be, in this order, the following entities:
Employee
Person
EmployeeSector
Sector
Sector
DailyReserve
Sector
If it is already like this, then you probably have some "deleted" attributes that the platform is not avoiding due to the use of the alias. In this case, the solution would be to clean the database from those deleted attributes. You can use DBCleaner and DBCleanerOnSteroids to perform this cleaning.
Hipe this helps.
Cheers.
P.S. Even being the same error, is always better to open a new Topic and make a reference to this one, for example.