Strange behaviour in SET_RE****T_OBJECT_PROPERTY

Hi,

I need to run a re****t from a Form.
The Re****t Parameter are stored in a table and with this parameters I
want to set the re****t properties

Now if I use this statement (this is an example):

SET_RE****T_OBJECT_PROPERTY(rep_id, RE****T_DESFORMAT,
MYTABLE.REP_DESFORMAT);


the property is set correctly.

But If I use this code:

DECLARE PR$Format VARCHAR2(100);
......
BEGIN
SELECT RE****T_DESFORMAT
INTO PR$Format
FROM MYTABLE
WHERE ........
SET_RE****T_OBJECT_PROPERTY(rep_id, RE****T_DESFORMAT, PR$Format);
........
END;


the parameter is not set.

And so for the others parameters. I do not understand this curious
behaviour.

Can anyone help me ?

Greetings...
Gaetano