Can anyone see why this stored procedure doesn't return any data.

I've executed the query seperately and it works fine.

TIA
Adam
-----

CREATE PROCEDURE "GET_IDENTIFIER_STRING"
(
"SYSTEM_NAME" VARCHAR(50),
"PERSON_ID" INTEGER
)
RETURNS
(
"IDENTIFIER_STR" VARCHAR(50)
)
AS

BEGIN
SELECT IDENTIFIER_STRING
FROM IDENTIFIER
WHERE RECORD_SYSTEM_ID =
(SELECT RECORD_SYSTEM_ID
FROM RECORD_SYSTEM
WHERE SYSTEM_NAME = :system_name
)
AND PERSON_ID = :person_id
INTO :identifier_str;
EXIT;
END
^