prolog 中出现太多参数错误

Question

customer(chuchi, goyal, 800.00).
customer(rishu, jain, 900.00).

get_cust_bal(X, Y, Z):-
    customer(chuchi, Y, 800.00),
    customer(X, Y, Z),
    format('owes me Bal ~w', [X, Y, Z]).

错误是

Format error: too many arguments
ERROR: In:
ERROR:   [11] format('owes me Bal ~w',[_4304,goyal|...])
ERROR:    [9] toplevel_call(user:user: ...) at c:/program files/swipl/boot/toplevel.pl:1162
ERROR:
ERROR: Note: some frames are missing due to last-call optimization.
ERROR: Re-run your program in debug mode (:- debug.) to get more detail.