I'm not really following what you're doing here. I gather that in column P you have values like:
Data type 1
Data type 2
etc.
But, if your VLOOKUP:
=VLOOKUP(P2,'[different workbook.xlsx]
Data type 1'!$A:$I,5,FALSE)
is referencing P2, that seems to be saying you're looking for a match with 'Data type 1' on '[different workbook.xlsx]Data type 1'. In other words, the equivalent of:
=VLOOKUP("Data type 1",'[different workbook.xlsx]Data type 1'!$A:$I,5,FALSE)
PS: For a demo of INDIRECT's use in conjunction with the OFFSET function (not necessarily relevant to your specific needs), see:
https://www.msofficeforums.com/excel...reference.html