Prolog implementation of SEND + MORE = MONEY isn't finding a result

I’m getting started with Prolog, and decided to try the famous SEND+MORE=MONEY puzzle, as it seemed fairly straightforward. However, my implementation does find a result.

Can anyone see what I did wrong?

smm([S, E, N, D, M, O, R, Y]) :-
  maplist(between(0, 9), [S, E, N, D, M, O, R, Y]),
  Line1 is           S*1000 + E*100 + N*10 + D,
  Line2 is           M*1000 + O*100 + R*10 + E,
  Sum   is M*10000 + O*1000 + N*100 + E*10 + Y,
  Sum = Line1 + Line2.

I’m not sure this is even the best way to approach this puzzle, so please feel free to make any (constructive!) comments on my code.

>Solution :

Just as you use is to compute the arithmetic expressions for Line1, Line2 and Sum, you need to use it for Line1 + Line2.