Error granting access to sequence with PostgreSQL 8.4
The syntax for GRANT in PostgreSQL 8.4 is

GRANT { { USAGE | SELECT | UPDATE }
    [,...] | ALL [ PRIVILEGES ] }
    ON SEQUENCE sequencename [, ...]
    TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]


You can't just exclude SEQUENCE. If you could it'd be in [], without which it's not optional.

GRANT USAGE ON SEQUENCE users_uid_seq TO myUser;


As a side note, PostgreSQL 8.4 was EOL on July 2014