Match function not evaluating correctly

[Robert Flanagan]

I have the following formula:

=MATCH("LAUNDRY", {"Laundry";"Misc Inc"},FALSE)

In one worksheet of a workbook created months/years ago, the formula returns
#N/A
In a new workbook, it evaluates fine, to the value 1
In a new worksheet in the workbook it evaluates fine, to the value 1
In the same workbook in another worksheet, it evaluates fine, to the value 1

Excel gives the comment "a value is not available to the formula or
function" in a popup available beside the cell in the problem worksheet

If I change LAUNDRY to Laundry, it evaluates fine.

There are very few formulas in the worksheets in the workbook, maybe 100.
There are cells entries, but most are blank. The data area on the two
sheets in the workbook is about 200 rows and 20 columns.

The calculation settings for the workbook are normal, and identical to a new
workbook, and ones that excel sets by default. No one had messed with them.

Any ideas on why this formula is not working? I know I can convert all text
to uppercase, but that should not need to be done.

frustrated!

Bob