Oracle eBusiness Suite :Purchasing :forms Personalization

Problem:

PO Summary screen so that, POs cant be finally closed if the billed quantity is not equal to the receipted quantity. 

When this is true: 
:DISTRIBUTIONS_FOLDER.QUANTITY_BILLED <> :DISTRIBUTIONS_FOLDER.QUANTITY_DELIVERED 

Hide  PO_DOCON_CONTROL.OK_BUTTON 

Solution :
In Conditions TAB 

Trigger Event : WHEN_VALIDATE_RECORD 
Trigger Object : PO_DOCON_CONTROL 
Condition : PO_DOCON_CONTROL.ACTION = 'FINALLY CLOSE'  and DISTRIBUTIONS_FOLDER.QUANTITY_BILLED <> :DISTRIBUTIONS_FOLDER.QUANTITY_DELIVERED 

In Actions TAB 

Seq = 1 
Type = Message 
Message Type = Show 
Message Text = You can not finally close the PO 
Seq = 2 
Type = Property 
Language = All 
Enabled is checked 
Object Type = Item 
Target Object = PO_DOCON_CONTROL.ACTION 
Property Name = VALUE 
Value = Leave it blank.