INDEX MATCH SMALL ROW, Double criteria Lookup

Hello,

Long time reader, first time poster. I'm at the end of my rope trying to figure out what I'm doing wrong here and could really use some help.

I have two workbooks. One is a large database (WorkBook I/UGLEEORANGE) with ISBNS, titles, corresponding author codes, etc. The second is a list (WorkBook II) of books with ISBNS. I am attempting to return multiple values of matching author codes in WBII. Once the author codes are determined I need to do a lookup into the database with double matching criteria to pull the authors 'share' of the book/ISBN.

To return the multiple results from the lookup value I am using this formula in column B (WBII):
=INDEX([UGLEEORANGE2.xlsx]No_Bookclub_etc!$L$2:$L$14657, SMALL(IF(A2=[UGLEEORANGE2.xlsx]No_Bookclub_etc!$O$2:$O$14657, ROW([UGLEEORANGE2.xlsx]No_Bookclub_etc!$O$2:$O$14657)-MIN(ROW([UGLEEORANGE2.xlsx]No_Bookclub_etc!$O$2:$O$14657))+1, ""), ROW(A1)))

It works for some (maybe 25%) of the spreadsheet, but the rest result in a #NUM error, that I can't figure out.

After I determine the answer for column B. I created a helper column (G in WBII and A in WBI) with the =CONCATENATE formula to serve as my double lookup criteria to find the 'author share' that should return in column M, but even this column will sometimes give me an #NA result even if I know there should be a match when the 'helper' column' is populated. I ate one point entered all of the author codes by hand before I was able to write the INDEX MATCH formula.

I can certainly just continue to search each ISBN and copy and past, but that is very time consuming and I will have to do this a few times a month and would much rather have a formula to save time.

Hopefully I have explained this fully.
I have attached the two workbooks.

Thanks in advance.


*** I had to remove a lot of data and rename the database workbook from UGLEEORANGE2 to uglyorange, so I could upload it onto the site.
https://www.dropbox.com/s/7r441c6myj...glyorange.xlsx

Hi AlKey,

Thank you for your input. Unfortunately, I do not have the Access to Access.

Is this the reason why I am getting the NUM return on my formula? Or is it the formula itself? I am self teaching and would like to know if I have made any mistakes in the formula and/or my though process on how to solve this.

Any assistance is appreciated.

Is it possible to look at the zip file I attached to my original query?

Thanks, Alkey. Will do.
The formula did work despite the large original file.