Prolog: Find out if sum of all list elements equals N -

i want check if values in list add value. far, have written following:

list_sum([head|tail], sum) :-     list_sum(tail, sum1),     sum head + sum1. 

however, when try list_sum([1,2,3,4], 10) prolog returns false. me out? don't know i'm doing wrong.

use clpfd!

 :- use_module(library(clpfd)). 

for calculating sum of list of integers use clpfd library predicate sum/3:

 ?- sum([1,2,3,4], #=, s).                 % q: 1+2+3+4? s = 10.                                   % a: sum 10  ?- sum([1,2,3,4], #=, 10).                % q: 1+2+3+4 equal 10? true.                                     % a: yes,  ?- sum([1,2,3,4], #=, 11).                % q: 1+2+3+4 equal 11? false.                                    % a: no, doesn't 

a use case showing benefits of using clpfd instead of (is)/2, suggested @capellic:

 ?- [a,b,c] ins 1..sup, sum([a,b,c,a], #=, 12), labeling([], [a,b,c]).    = b, b = 1, c = 9 ;  = 1, b = 2, c = 8 ;  = 1, b = 3, c = 7 ;  = 1, b = 4, c = 6 ;  = 1, b = c, c = 5 ;  = 1, b = 6, c = 4 ;  = 1, b = 7, c = 3 ;  = 1, b = 8, c = 2 ;  = c, b = 9, c = 1 ;  = 2, b = 1, c = 7 ;  = b, b = 2, c = 6 ;  = 2, b = 3, c = 5 ;  = 2, b = c, c = 4 ;  = 2, b = 5, c = 3 ;  = c, b = 6, c = 2 ;  = 2, b = 7, c = 1 ;  = 3, b = 1, c = 5 ;  = 3, b = 2, c = 4 ;  = b, b = c, c = 3 ;  = 3, b = 4, c = 2 ;  = 3, b = 5, c = 1 ;  = 4, b = 1, c = 3 ;  = 4, b = c, c = 2 ;  = 4, b = 3, c = 1 ;  = 5, b = c, c = 1.