prolog sort/4 undefined procedure built in -

i trying use supposedly built in procedure in swi-prolog. procedure in question sort/4.

the thing is, when try use in program following error:

error: undefined procedure: sort/4 error:     however, there definitions for: error:         msort/2 error:         sort/2 

i don't understand because documentation says built-in, prolog doesn't know it. need use procedure

would know how fix issue ? thought matter of library , tried add ":- use_module(library(lists))." @ beginning of code situation remains same.

hope can me, have day

the sort/4 predicate documented here relatively new. if latest stable or development version of swi-prolog should available. built-in, not part of library.