Following the discussion until now, I have a couple of questions.
1. If I understand you correctly, you have pinpointed your problem down
to the formula returning #N/A because J33 itself is #N/A, J33 being the
result of a lookup which failed. Is this correct?
2. What do you mean by "correct"? Avoid the error value and return
blank or a message of choice? If J33 required a value to be found and
the value was not found it is reasonable that a query based on J33 will
return "not found" in any form.

If you want to trap the error of J33 then you could use
IF(ISNA(J33),a,b). But what could these values a, b be? Whatever they
are, either they will not be in your lookup table
('2006 Discount Grid'!$A$1:$O$386) or they could default to a certain
value (unlikely).

So I suggest you specify more clearly what it is you want to avoid.

HTH
Kostis Vezerides

That shouldn't matter, excel will read the value result of the vlookup, not
the formula itself.

You have another issue producing the #N/A