Variable row not defined

Variable row not defined

For my orders form I am trying to auto populate price field (sourced from product form) in an order details subform based on the selected subform product choice.  A very common requirement.  I have tried using the code below (found on a zoho blog) but it isn't working for me.  I keep getting the error message on the second line of code  

Variable 'row' is not defined

//Fetches the information from the "Products" table
selected_Product = Products [Code =  row.Order_Items];
//Updates the value of Unit Price using the stored value from "Products" table
row.Unit_Price = selected_Product.Price;