Forms :: Quit From Form With Items Having Primary Key?

I have build a form based on a table with 2 columns,one of which isprimary key. I have created a Button with name "Quit".For that i used when-button-pressed trigger with built in "exit_form". But when I run the form,with out any execution of query or any action if I press "Quit" button,it is not working

The error message is "FRM-40202 : Field must be entered" Then I used a trigger to the item with primary key.when-new-item-instance:

set_item_instance_property('CUTOMER.CUSTID',CURRENT_RECORD,REQUIRED,PROPERTY_FALSE);

While using this,the error is "unable to resolve reference to item customer.custid" Cutomer is block name & custid is textitem with primary key. canvas used is Tab canvas with 3 tab pages with master detail relation b/w thwm. The primary key is required compulsory at the time on inserting.