You have a few options....Here are two:

First, if you want to VLOOKUP a concatenated combination of the values from
A2 and B1, then you'll need the left column of the lookup range to contain
those values.

You could achieve that by doing this:
1)Insert a cells at the front of the range (shifting Col_A to the right)
2)A35: =B35&C35 (copy that formula down)
3)Your new formula in B2 would change to:
=VLOOKUP(A2&B$1,A$35:E$38,5,False)

OR....
You could just use this formula with your current structure
B2: =INDEX(D:D,SUMPRODUCT((A35:A38=A2)*(B35:B38=B1)*RO W(D35:D38)))

Notes:
If there will be duplicate matching combinations, the first formula will
return the first "hit". The second formula will be completely wrong. There
are workarounds to prevent that, so let us know if you run into issues with
duplicates.

Is that something you can work with?
Post back with any questions.
***********
Regards,
Ron

XL2002, WinXP


"pm" wrote:

I've tried to illustrate my problem:

"NameID" is A1, "rs10170160" is B1, etc. Array data starts at A35

Name ID€¦..rs10170160
70001-1€¦..(formula here)

Formula: =vlookup(A2&B$1,A$35:E$38,4,False)

Array: (note, column C here is programmed in as =A35&B35)

70001-1€¦..rs10170160€¦..70001-1rs10170160€¦..C€¦..T
70001-11€¦..rs10170160€¦..70001-11rs10170160€¦..C€¦..T
70002-1€¦..rs10170160€¦..70002-1rs10170160€¦..C€¦..T
70002-13.....rs10170160.....70002-13rs10170160.....T.....T

Why does my formula keep returning NA when it should return a "C"??

Thanks in advance!