[postgresql] Postgresql: error "must be owner of relation" when changing a owner object

What is the grant option/trick I need to give to the current user ("userA") to allow him to change a object's owner which belongs by another user ("userC")?

More precisely, the contact table is owned by the userC and when I perform the following query for changing the owner to the userB, connected with the userA:

alter table contact owner to userB;

I get this error:

ERROR:  must be owner of relation contact

But userA has all needed rights to do that normally (the "create on schema" grant option should be enough):

grant select,insert,update,delete on all tables in schema public to userA; 
grant select,usage,update on all sequences in schema public to userA;
grant execute on all functions in schema public to userA;
grant references, trigger on all tables in schema public to userA;
grant create on schema public to userA;
grant usage on schema public to userA;

Thks

Command line output:

root@server:~# psql -U userA myDatabase
myDataBase=>\dt contact
    List of relations
Schema |  Name   |   Type   |  Owner
-------+---------+----------+---------
public | contact | table    | userC
(1 row)
myDataBase=>
myDataBase=>alter table contact owner to userB;
ERROR:  must be owner of relation public.contact
myDataBase=>

This solved my problem : Sample alter table statement to change the ownership.

ALTER TABLE databasechangelog OWNER TO arwin_ash;
ALTER TABLE databasechangeloglock OWNER TO arwin_ash;

From the fine manual.

You must own the table to use ALTER TABLE.

Or be a database superuser.

ERROR: must be owner of relation contact

PostgreSQL error messages are usually spot on. This one is spot on.