Hi Mike,
I think the problem is that you are missing the FALSE from the first
VLOOKUP. Without it, the error trap fails, then the IF function goes to the
second VLOOKUP, which does have a FALSE, and so produces the error. Try:
=IF(ISERROR(VLOOKUP(A6,H7:M121,3,FALSE)),"",VLOOKU P(A6,H7:M121,3,FALSE))

Regards - Dave.