Last date of the month when submitting a concurrent program

Hello Experts,

PROBLEM DESCRIPTION
===================
Have a date parameter in a concurrent progrm.
Default Type: SQL Statement
SQL to get last date: select last_day(sysdate) from dual

When submit this program standalone then there is no problem.
For example: Submit on 10-JAN, it will show 31-JAN.
             Submit on 23-JAN, it will show 31-JAN.  

The issue starts when scheduling this program to run once everyday.
When it goes to next month to February, the date value still remains 31-JAN

QUESTION
========
Any suggestion to resolve this type of issue.
Is there any Metalink document can be followed ?