Date Picker null after page submit

Question

Hi,
I have created an application with two regions. On one region a select statement displays the list of employees with their employee id's. On other region there is a select statement which shows the leave detail of every employee using range of date on where clause of select statement. Two date picker items are created on region one. when a name of employee is clicked on region one the employee id of that employee uses select statement in second region and its information should display. It is working well without date range. when I use dates in where clause it shows no data because date pickers goes null after page submit. Page is branchig to same page.
I am not able to resolve why date pickers goes null.
Oracle Database 11G
Apex Version 3.0
Sajjad

Answer 1

In region one select statement retreives employee id's and there is also search item on region one searching employee names and it retain the value. but date pickers having same setup that you mentioned dos'nt retain values. If they retain values my problem will solve.
When cliked on employee id select statement should execute using employee id and date picker values on another region on same page.