You can check all the records with
=COUNTIF(H1:H20,"#N/A")
or with AutoFilter showing rows with #N/A. I am assuming your'e using FALSE
as the 4th arg in VLOOKUP.

Two causes for #N/A:
Forget to use absolute columns in the Table reference.
Entries in the left column are formatted as text instead of numbers or
visa versa.

"Becksicle" wrote:

Hi,

I am working with quite a large amount of data, I have 2 workbooks, they
have one common column - ID, I am pulling information from workbook 1 (48K
records) into workbook 2 (110K records in csv) using a vlookup on the ID
column.

The formula is correct and works for all but about 3,500 records. At first I
thought that these records might not have a corresponding ID, but whilst
doing a couple of manual checks I found that the data was there and just
wasn't coming through. Also the records are grouped together, obviously I
can't check 3,500 records, but I have found over 20 consecutive rows that
aren't coming over into workbook 2, around about the 36,500 mark in book 1.

I have tried re-writing the Vlookup, narrowing the lookup criteria and it
still doesn't work. There seems to be some kind of problem reading the data
in the middle of the workbook.

Has anyone seen anything like this before? Any ideas?