Question about granting permissions

Hi,

Sorry to bother with the stupid question guys - I'm new to the Postgres.
I'm having issue allowing user to access the database - the user is
not allowed to access the data. I do the following:
1) grant all on database testdb table mytable to trinity;

postgres=# \l
List of databases
Name | Owner | Encoding | Collation | Ctype |
Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres
:
postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres
:
postgres=CTc/postgres
testdb | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =Tc/postgres
:
postgres=CTc/postgres
:
trinity=CTc/postgres
(4 rows)

But when I login (psql -d testdb -U trinity) as trinity and check it,
it doesn't work.

testdb=> select * from mytable;
ERROR: permission denied for relation mytable
testdb=> \dp
Access privileges
Schema | Name | Type | Access privileges | Column access privileges
--------+---------+-------+-------------------+--------------------------
public | mytable | table | |
(1 row)

There is also entry in the log:
2012-08-26 13:06:01 CEST testdb trinity ERROR: permission denied for
relation mytable
2012-08-26 13:06:01 CEST testdb trinity STATEMENT: select * from mytable;

Can someone explain what do I do wrong? Thank you in advance!

Cheers