Forms :: Dynamic List Items

I want to create two list items. one is for deptno and another is for empno in a single form.

Based on the selected deptno value from first list item i want to populate corresponding empno from second list item. I tried with the fallowing code, it's work fine but the second list is not clears with the existing empno's.

Code for Deptno List item

declare
cursor c is select deptno from dept;
cnt number := 1;
begin
clear_list('LI_DEPTNO');

[Code]...

Code for Empno list item in when_list_changed trigger for deptno list item

declare
cursor c is select empno from emp where deptno = :LI_DEPTNO;
cnt number := 1;
begin
it_id := Find_Item('LI_EMPNO');
clear_list(it_id);
for i in c loop
add_list_element('LI_EMPNO',cnt,i.empno,i.empno);
cnt := cnt + 1;
end loop;
end;