bug in function arguments "recognition"

I've a function defined as:

create or replace function catalog_relateditems(__itemid bigint,
  families int[]...

I call it with

select * from catalog_relateditems(6538::bigint, ARRAY[1,2,3,4,5]);
and I get:

HINT:  No function matches the given name and argument types. You
might need to add explicit type casts.

The I try to drop the function using psql autocomplete and I get...

DROP FUNCTION catalog_relateditems ( bigint, integer[], character
varying)

\df *rela*
reports:

public     | catalog_relateditems   | setof record     | __itemid
bigint, families integer[], OUT ...

There is no other function named catalog_relateditems

I'm on 8.3.9 debian lenny

--
Ivan Sergio Borgonovo
http://www.webthatworks.it