If your NetSuite formula expression is returning an error, odds are NULL is involved.

NetSuite saved searches see zero and NULL as completely different animals. Logically, when say thinking how many of “X” you have on order, you would think it is either some number or zero. But nothing on order is literally no value or NULL. It is a blank, empty field.

So when making formulas, we need to account for NULL. It looks something like this (using whatever fields you are calculating):

NVL({item.quantityonorder} * {cost}, 0)

Constructing formulas in NetSuite is often not straightforward. But remembering to handle NULL is a great way to troubleshoot any time you return an ERROR: INVALID EXPRESSION in saved searches.