LOV Event or WHEN-VALIDATE-ITEM in Form Personalization

 Hi All,
How to fire some actions when user selects / changes the organization from the LOV in Assignment Form using Form Personalization.

I have tried with WHEN-NEW-ITEM-INSTANCE on Organization field.. But the trigger is getting fired when you click / move the cursor to the field. Its not firing when user selects / changes the Organization from the LOV.

Is there any alternative way to achieve this.

Thanks in Advance.