show calendar in a date field in custom form

Hi,

I am developing a custom form in oracle apps r12

and I want to show calendar lov in a date field

I have copied template form and rename it and did the following

but no vain

subclass:text_item_date

LOV: ENABLE_LIST_LAMP

validate from list: no

and in item trigger key_list_val

I add this

calendar.SHOW;

any help PLS