Matching email addys to same names on different lists

Hello - Someone posted exactly what I'm trying to do, and then someone posted a response, on this site but I'm having a problem and hope someone can help me out. I posted the original question and answer below.

I have two sheets - sheet one with 7908 and sheet two with 14388 rows. When I use the formula, below, and adjust the row numbers accordingly to 14388, I get different results every time I run it. Sometimes it will match some - and those are always towards the bottom of the sheet - and sometimes it matches none. And everytime I run it it misses many.

Any ideas on how that could happen? I'm not changing anything - the same exact formula (cut and pasted) in the same place in the same file yet always different results and it never gives complete results.

Thanks for any help!!!
Rob

Here is the original question and answer…..

Question:
I have a customer list of around 6000 names and addresses. I have a separate list of names with email addresses. Is there a way for me to do some sort of lookup function to get the email addresses pulled from the one list and put to the corresponding names on the other list. I need it to check for both first and last names due to the fact that I have a lot of duplicate last names. Thanks in advance for any help on this.

Answer:
So assuming the first and last names are separate columns, then something like:

=INDEX(Sheet2!$C$2:$C$6000,MATCH(1,INDEX((Sheet2!$A$2:$A$6000=A2)*(Sheet2!$B$2:$B$6000=B2),0),0))

copied down

where Sheet2!A2:C6000 is the lookup table and you are maching up A2 and B2 of active sheet to columns A and B of Sheet 2 to get column C addresses.

Hello TMS,
Thanks for the quick response!
Unfortunately, that didn't have any impact - still getting no results, or incorrect results. No matches ever appear above row 6500 or so - even though there are many matches there.
Also, in Excel 2013, I just noticed there are characters, within the formula, that are showing up in different colors - red, green, pink….most notably the "A2" and "B2" that appear right after "14388=".

Thanks!
Rob

Hey Everyone,
You're going to kill me! lol

There was a leading space in the first 2/3's of the sheet. I finally noticed it that, where the matches started, was actually where I pasted info from another sheet - then it was just a question of finding out what the difference between them was.

I still don't understand how that could impact the results being "different" on multiple occasions.

But, since I removed the leading spaces, the results have been static. So it looks like I'm all set.

Thanks for your and your patience!

Rob