Points need to stored when submitting the form in web application

Hello Team 
Actually there is requirement like user has to fill the form regarding the loyalty program 
When they have submitted additionally the points has to be stored in respective schema attribute.
and There is a 2 pages in web app 
1 st page is to record the users interest on loyalty program 

2nd page is simply thankyou page.

and we do have preload activity and storage activity to store and update 

FYI :Here is the script used in javascript activity to store additionally 50 points in schema attribute placed this after a page activity

But getting this error also ponits values not stored

and this is the flow of web app