pg_stat_statements enabled, but the table does not exist

I've postgresql-9.4 up and running, and I've enabled pg_stat_statements module lately by the help of official documentation.

But I'm getting following error upon usage:

postgres=# SELECT * FROM pg_stat_statements;
ERROR:  relation "pg_stat_statements" does not exist
LINE 1: SELECT * FROM pg_stat_statements;


postgres=# SELECT pg_stat_statements_reset();
ERROR:  function pg_stat_statements_reset() does not exist
LINE 1: SELECT pg_stat_statements_reset();

I'm logged in to psql with the postgres user. I've also checked the available extension lists:

postgres=# SELECT * FROM pg_available_extensions WHERE name = 'pg_stat_statements'
;
        name        | default_version | installed_version |                          comment                          
--------------------+-----------------+-------------------+-----------------------------------------------------------
 pg_stat_statements | 1.2             |                   | track execution statistics of all SQL statements executed
(1 row)

And here's the results of the extension versions query:

postgres=# SELECT * FROM pg_available_extension_versions WHERE name = 'pg_stat_statements';
        name        | version | installed | superuser | relocatable | schema | requires |                          comment                          
--------------------+---------+-----------+-----------+-------------+--------+----------+-----------------------------------------------------------
 pg_stat_statements | 1.2     | f         | t         | t           |        |          | track execution statistics of all SQL statements executed
(1 row)

Any help will be appreciated.

Extension isn't installed:

SELECT * 
FROM pg_available_extensions 
WHERE 
    name = 'pg_stat_statements' and 
    installed_version is not null;

If the table is empty, create the extension:

CREATE EXTENSION pg_stat_statements;