Override Unit Amount Calculation

Hi All,

Need help on field service functionality.

I am trying to override the unit amount of Work Order Products and Services using JavaScript. I've created a new field for the New Unit Amount. The Script that copies the New Unit Amount to the Unit Amount(OOB) is working fine. But when I changed the "Line Status" field, it retrieves the Product's Unit Price instead of replacing it with the New Unit Amount. I added the script on the Line Status' on change event but it still doesn't work. 

Appreciate any help. Thank you.