Ken ... a bit more the story, sorry to confuse you.
First, to answer your question ---- The symptom is not an error message, but rather a non-active response ... equation of formula in the major totals cell, referencing the shorter subtotal strings, but no activity occurs in the major total cells.
To be honest, I'd not "visited" these spreadsheets until I am now facing an upgrade. The users were happily working with them for several years. The purpose is to provide them subtotals and final total that change the instant they change the value of an item cell, and immediately see the results such an action would take overall.
Thinking back, I now recall that there are far more cell addresses in the formula than I described originally.
I have multiple projects with subtotals. As I step down through them, I am gathering their subtotal cell addresses into a string for the overall total. (I suspect the strings are too long as a result.)
I also recall that, last time, I had to "fool" Excel by "parking" shorter strings of the [project subtotals'] cell addresses being referenced off to the right, out of the clients' view of course, to avoid running into a "length of string" problem with the final total's formula string. (Yup, Excel has its limitations.) Here's the full instruction that results:
Worksheets("Sheet1"
.Range("B315"
.Formula = "=SUM($B$18, $B$43, $B$110, $B$137, $B$146, $B$162, $B$174, $B$179, $B$183, $B$186, $B$193, $B$204, $B$212, $B$216, $B$221, $B226, $B$231, $B$236, $B$242, $B$246, $B$265, $B$269, $B$285, $B$190, $B$297, $B$313)"
So, now, I'm fiddling with parsing the subtotal cell string again, and debugging. I've tried to [neatly] gather the subtotal cell addresses, vertically aligned and hiding the rows containing the shortened strings ... but the major total cell will not work with those cell addresses after they are hidden and then referenced by the major total cells. I'm guessing that I might have to use the original method of placing the subtotal strings off to the right again, out of the user view again and not "hiding" them.
But, thanks anyway for taking the time to experiment with me.
Regards, Sandy