[ADMIN] cfg pg_stat_statements in PG 9.5 error

Hi List ,
I am seeing the following issue:
I have to cfg  pg_stat_statements in  Pg version 9.5.1: I  create the
extension inside db , next cfg:

local_preload_libraries =
'/usr/pgsql-9.5/share/extension/pg_stat_statements'

when re-starting the PG server seeing this in errorlog :
FATAL:  access to library
"/usr/pgsql-9.5/share/extension/pg_stat_statements" is not allowed

I have root with full permission to the "/usr/pgsql-9.5/ and user
postgres with exec only , what I am missing form this cfg?