Script failed on Formcalc

Hello!

I have created a total sum calculation in a table using formcalc, which works when the pdf is open in reader. The issue is that an error message occurs upon opening the document & when entering the numbers. However, all the tables calcuate the sum correctly...

Here is the error message:

Is there a way to identify the location of the error? or is this something that requires rewriting the script?

I am not familiar with writing script.. so I was heavily relying on FormCalc..

Thank you for any advice!