#REF! error when copying formula beyond row 65536 in Excel 2007

[Bandicoot]

I have a worksheet and want to copy a formula down below 65536 rows.
Everytime I copy the formula, it substitues "#REF!" for one of the
references as soon as the formula goes into row 65537. It doesn't matter what
I seem to do.
The formula is rows 1 to 65536 works fine as is:
=IF(AND(C65536>1,C65536<99),fpsywbfromdbrh(D65536,C65536/100,$D$1),NA())
When this formula is copied into row 65537 (and below), the formula becomes:
=IF(AND(C65537>1,C65537<99),fpsywbfromdbrh(#REF!,C65537/100,$D$1),NA())
Any suggestions or fix?

 

[Dave Peterson]

Maybe the person who wrote the fpsywbfromdbrh user defined function never
thought that there would be more than 64k rows. (More rows were added in
xl2007.)

I think I'd go back to that developer.