A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Sorry - didn't see that. I just test it by first pasting the formula into B3 exactly as you have it but nothing happened, ie. the formula seemed to just be entered as text, not a formula. I then tried:
=VLOOKUP(
IF(ISNA(VLOOKUP($A1,[test.xlsx]Home!$A$1:$AQ$61,$B$2,FALSE))
IF(ISNA(VLOOKUP($A1,[test.xlsx]Billing!$A$1:$AQ$118,$B$2,FALSE)),IF(ISNA(VLOOKUP($A1,[test.xlsx]Work!$A$1:$AQ$33,$B$2,FALSE)),IF(ISNA(VLOOKUP($A1,[test.xlsx]POBox!$A$1:$AQ$11,$B$2,FALSE)),VLOOKUP($A1,[test.xlsx]POBox!$A$1:$AQ$11,$B$2,FALSE),"NO MATCH ANYWHERE"),VLOOKUP($A1,[test.xlsx]Work!$A$1:$AQ$33,$B$2,FALSE)),VLOOKUP($A1,[test.xlsx]Billing!$A$1:$AQ$118,$B$2,FALSE)),VLOOKUP($A1,[test.xlsx]Home!$A$1:$AQ$61,$B$2,FALSE))
)
But that didn't work either. Am I supposed to put your formula into B3 exactly as is?