Fwd: Have a problem with citext

Begin forwarded message:

From: Sadek Touati <bilal2dellys@hotmail.com>
Subject: Have a problem with citext
Date: September 29, 2017 at 17:02:50 EDT
To: "david@kineticode.com" <david@kineticode.com>

Dear sir,
I'm using the citext datatype in my application. I have PostgresSql 9.6 installed by EnterpriseDB

psql mydatabase postgres
create extension citext with schema myschema

\c mydatabase biguser

set search_path to myschema;

create table tst(v citext);
insert into tst values('sadek');

select strpos(v, 'd') from tst;

ERROR: permission denied for function strpos

select strpos(v, 'd'::citext) from tst; (If I read the documentation correctly this should work! alas, it doesn't)

ERROR: permission denied for function strpos

select strpos(v::citext, 'd'::citext) from tst;

ERROR: permission denied for function strpos

select strpos(v::citext, 'd') from tst;

ERROR: permission denied for function strpos

select strpos(v::citext, 'd'::citext) from tst;

ERROR: permission denied for function strpos

select strpos(v::text, 'd'::text) from tst;

strpos
--------
3
(1 row)

Am I missing something here?

thanks in advance