First of all sorry for my bad english.
I have a server where i create and publish my datasource. In a DataSource i have a calculated filed with dd/mm/yyyy and it work.
+ LEFT([Date Creation] ,4)
=> my result is for exemple : 30/09/2018
When i publish the DataSource the field become mm/dd/aaaa.and the date is wrong
=> My result is wrong => "null"