System doesnt compare dates of PD in top down scheduling

Hi All,

I have a query. In a project structure, at project definition  i am using scheduling scenario - Top Down . There is a 4 level of WBSEs and network/activites assigned to the 4th level WBSEs . When i save system checks the date of activites lies withing date of 4th level WBSE , and date of 4th level WBSE within date of 3rd level WBSE , this goes till 1st level WBSE. But system does not compare the date of 1st level WBSE with the date of project definition.

For eg: Start date at PD = 31.01.2008

            Finish date at PD= 31.12.2019

At 1st level WBSE

Basic Start date= 01.01.2001

Basic End date =  31.12.2016

When i save , system doesnt give date conflict error and allow to save the project. So i just want to know how can i make system to compare date of 1st level, WBSE with dates of project definition.

Thanks.