nested if doesn't work

[Guest]

This formula doesn't work, it looks like it should work:

=IF(ISNA(VLOOKUP(B4,'07-17-07'!B5:I70,8,FALSE)),
IF(ISNA(VLOOKUP(B4,'07-10-07'!B5:I66,8,FALSE)),
VLOOKUP(B4,'07-03-07'!B5:I66,8, FALSE), VLOOKUP(B4,'07-10-07'!B5:I66, 8,
FALSE)), VLOOKUP(B4,'07-17-07'!B5:I70,8,FALSE))

If I do the lookups separately they work.

 

[Guest]

Sorry my fault,The nested if does work, it was a lot of typos.