I get error as "duplicate key value violates unique constraint " - postgresql

Question

I'm working on a data warehouse. I have 4 table on public schema they are customer, product, addressee and orders
Then I created this tables on my olap schema
CREATE TABLE olap.time
(
idtime SERIAL NOT NULL PRIMARY KEY,
year integer,
month integer,
week integer,
day integer
);
CREATE TABLE olap.addressees
(
idaddressee integer PRIMARY KEY NOT NULL,
name varchar(40) NOT NULL,
zip char(6) NOT NULL,
address varchar(60) NOT NULL
);
CREATE TABLE olap.customers
(
idcustomer varchar(10) PRIMARY KEY ,
name varchar(40) NOT NULL,
city varchar(40) NOT NULL,
zip char(6) NOT NULL,
address varchar(40) NOT NULL,
email varchar(40),
phone varchar(16) NOT NULL,
regon char(9)
);
CREATE TABLE olap.fact
(
idtime integer NOT NULL,
idaddressee integer NOT NULL,
idcustomer varchar(10) NOT NULL,
idfact integer NOT NULL,
price numeric(7,2),
PRIMARY KEY (idtime, idaddressee, idcustomer),
FOREIGN KEY (idaddressee) REFERENCES olap.addressees(idaddressee),
FOREIGN KEY (idcustomer) REFERENCES olap.customers(idcustomer),
FOREIGN KEY (idtime) REFERENCES olap.time(idtime)
);
After the creating tables I run these queries
INSERT INTO olap.time (year, month, week, day)
SELECT date_part('year', date), date_part('month', date), date_part('week', date), date_part('day', date)
FROM public.orders
GROUP BY public.orders.date
ORDER BY public.orders.date;
INSERT INTO olap.addressees(idaddressee, name, zip, address)
SELECT idaddressee, name, zip, address
FROM public.addressee;
INSERT INTO olap.customers (idcustomer, name, city, zip, address, email, phone, regon)
SELECT idcustomer, name, city, zip, address, email, phone, regon
FROM public.customer;
And then I try to do these set of query
INSERT INTO olap.fact (idtime, idaddressee, idcustomer, idfact, price)
SELECT olap.time.idtime, olap.addressees.idaddressee, olap.customers.idcustomer, COUNT(*), public.orders.price
FROM (((public.orders
INNER JOIN olap.time ON (date_part('year', public.orders.date) = olap.time.year AND date_part('month', public.orders.date) = olap.time.month AND date_part('week', public.orders.date) = olap.time.week) AND date_part('day', public.orders.date) = olap.time.day)
INNER JOIN olap.addressees ON public.orders.idaddressee = olap.addressees.idaddressee)
INNER JOIN olap.customers ON public.orders.idcustomer = olap.customers.idcustomer)
GROUP BY olap.time.idtime, olap.addressees.idaddressee, olap.customers.idcustomer, public.orders.price;
After running last set of queries I got error
ERROR: syntax error at or near "duplicate"
LINE 1: duplicate key value violates unique constraint"
What can the problem be? Thanks in advance