And regarding your issue, you could use this formula:
=SI.ERROR(INDICE(A2:A16;COINCIDIR(C18&"_"&C19;F2:F16&"_"&L2:L16;1));"no file to process") -----> in english: =IFERROR(INDEX(A2:A16,MATCH(C18&"_"&C19,F2:F16&"_"&L2:L16,1)),"no file to process")
but the approximated MATCH requires that the data set is sorted by the search criteria, in this case, column F and then column O; otherwise it won't work properly.
Regards!
EDITED (SirJB7)
Fixed column from O to L. Debraj(ex-Roy)'s catch.
@Debraj (ex-Roy)
Hi, buddy!
You're right... will be an earthquake today?
However I now realize that it can be solved with SUMPRODUCT, so I leave it to you. Good luck.
Regards!