Use Index Match Large to list top x entries

[RichP]

Hi,
Been a while since I posted here, sorry for the absence, but I'm stuck again!

I have a data table A2:AZ400; only 200 rows contain data thus far
On a second sheet I have a "Top 20" list that fits into B3:M32.

Using the formula =INDEX(Data!$A$2:$AZ$400,MATCH(LARGE(Data!$A$2:$AZ$400,$B3),Data!$A$2:$AZ$400,0),1) I can find the largest number in Column AZ ($B3 returns a 1), and use that as my first Top20 entry, using the column number at the end (in the example here "1") I can grab data from the corresponding columns. It is copied down and across to fill B4:M32, and works quite nicely as I play around with the data, adding and modifying lines in the original data table.

However, if I create a helper column in BA with a category that only yields 10 entries, and modify the formula to look at that for the LARGE function, my top 20 table is populated with the 10 entries, and then it repeats the very first row of the data table for the remaining 10 entries.

Any tips on how I stop this from happening, and why it is doing so?

Thanks!