Problem with functions

I been trying to create several different functions
that mimic several stored procedures in MSSQL.
The SQL works fine in an interactive SQL, but fails
miserably when I try to run/execute a function created
using that same SQL.
I have been searching web sites and reading what I
find but I have not anything on functions that speaks
about the issue I'm having.

I'm hoping maybe you can provide some input on how to
get these functions to work. I am including one of my
functions as sample.

Here's the function:
CREATE OR REPLACE FUNCTION "public"."getappts" (text,
date, date)
RETURNS SETOF "public"."calendar" AS'
SELECT *
FROM calendar
WHERE
event_date BETWEEN $2 AND $3
AND agent_number IN
( SELECT agent_number FROM agents
WHERE rel30a = $1 OR
agent_number = $1 )
ORDER BY event_start_time;
'LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT
SECURITY INVOKER;

Yes, I need to return multiple rows in the result set.
The two tables have the 'agent_number' column in
common, ie it is really a foreign key. But it is not
set up that way, it's not my database and I can not
change it.

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