create function (plgsql): permission denied

Greetings,

I have a user, owner a schema, but I just can't create any function
plgsql through that user. I got the error message: "plpgsql: permission
denied".

I don't know how can I grant permission to create functions for that
user (preferable way) or trust plpgsql language as a trusted language
(alternative way).

These are my definitions languages:

select * from pg_language ;
lanname | lanispl | lanpltrusted | lanplcallfoid | lanvalidator | lanacl
----------+---------+--------------+---------------+--------------+--------
plpgsql | t | f | 20893 | 0 |
sql | f | t | 0 | 2248 | {=U}
internal | f | f | 0 | 2246 | {=}
c | f | f | 0 | 2247 | {=}

In addition, could anyone explain me these table attributes?

thanks,
Pedro Salazar.
--
PS
pedro-b-salazar(at)ptinovacao(dot)pt
PGP:0E129E31D803BC61