ERROR: relative path not allowed for COPY to file

Hi,

I must be being thick - can anyone tell me what I'm doing wrong?

postgres=# COPY post_e_n
postgres-# TO 'usr/local/psql/csv/post_e_n.csv'
postgres-# WITH DELIMITER ','
postgres-# CSV HEADER;
ERROR: relative path not allowed for COPY to file

COPY (SELECT * FROM post_e_n) gave me the same error.

I did chmod 755 -R psql to make sure the directory could be written to. Is
this to do with the underscores? There is no csv file pre-existing in the
directory.

Thanks,

Andy