With your colleagues help I was able work with custom function, but there's problem when I tried to modify the code myself, it doesn't work, and I found out that when the field name is with space in between, it will not react, please advise how to overcome this. It's not the problem of the function itself as the function works when the destination field is a single word.
Field name that works : "Debit"
Field name that does not work : "Debit Note" <<<< there's a space in between
I tried
"Debit Note"
"DebitNote"
"Debit_Note"
all 3 and none of these will work, please advise and thank you