Forms :: Different Output In 6i And PL/SQL

Here i have one PL/SQL block which will returns the age of an employee using his id.

SET SERVEROUTPUT ON;
DECLARE
v_num NUMBER;
v_days NUMBER;
[code]...

It will returns an output of 27..I tried the same in Forms 6i using a text field and a button with a trigger "when_button_pressed". when i am entering the same id of employee i am getting a totally different answer

DECLARE
v_num NUMBER;
v_days NUMBER;
BEGIN
SELECT to_date(sysdate)-to_date(dob)
INTO v_num
FROM customer_details
WHERE application_id=:block3.day;
v_days :=floor(v_num/366);
MESSAGE(v_days);
MESSAGE(v_days);
END;

It is giving me a result of -73...i cleared my problem. but i cound not understand the internal work happening inside the forms and pl sql machine.