I named the files as File1.xlsx and File2.xlsx to match your formula. For testing I have 2 rows in each file as follows.

File1.xlsx has:
A1=johnny B1=34
A2=lanny B2=24

File2.xlsx has:
A1=lanny B1=u.s.
A2=jim B2=u.k.

File1.xlsx:
C1 has:
=IF(ISERROR(VLOOKUP(A1,[File2.xlsx]Sheet1!$A$1:$B$200,2,0)),"",VLOOKUP(A1,[File2.xlsx]Sheet1!$A$1:$B$200,2,0))

It does not replace the formula with a value. I don't see a place to attach files when I reply to your message. Otherwise I'll attach the files.