I have no idea why changing the iteration setting should have replaced those references with the REF error -- Excel has never done that to me. I observe that row 5 is the only active row in the spreadsheet you attached to post #1, and it seems quite likely that one would have deleted (not just cleared) row 4 in prepping the sample file, which would have created those REF errors. This formula in B5 does not seem to be part of the circular logic, so I am not sure how much effort to spend on this formula where the main concern is the circular logic in A5 and F5.