One last question to you guys. The report that, I'm working on is the quarterly report. When I change the @start date to (10/01/2014) on report, other three (@End, @NextStart, @NextEnd) parameters still show the same date.

When @start date is changed to (10/01/2014), as per the SSRS expression:

@End should change to 10/31/2014

@NextStart should change to 11/01/2014

@NextEnd should change to 11/30/2014

Thank you for your patience Rxm & Jack.