Issue in assigning the value to a field on User Input

Issue in assigning the value to a field on User Input

I try to create the Sales Order form in creator. I've created  two forms named "Order Form" & "Order Line Item". 

"Order Form" has the  sub form  "Order Line Item". In "Order Line Item" form, I've two fields named "Products" & "Unit Price".

"Products" is zoho CRM field for Products module & "Unit Price" is float type. I tried to assign the "Unit Price" while 

selecting "Products". I wrote the following script on  Field Actions --> Products --> On User Input

Script:

row.Unit_Price = 10000.0 ;

When I running the app, Unit Price has retained nothing even after chosen the product. 

I don't know what is wrong with this. 

Please give solution for this. 

Thankyou,
Ferozkhan