I have a excel array with multiple values. Some are less than 256 characters and some have a length greater than 256.
When I tried to do a VLookup using a sample str
If you are using VLOOKUP like this
=VLOOKUP(A2,D2:Z10,3,FALSE)
i.e. looking up A2 in D2:D10 and returning a result from F2:F10 then try this formula instead
=INDEX(F2:F10,MATCH(TRUE,INDEX(D2:D10=A2,0),0))
change ranges as required
Edit:
I mocked up a sample here - values in A2:A10 are the same as G2:G10 but in a different order. The length of each of those values is shown in column B, the VLOOKUP in column C fails on col A values > 255 chars but the INDEX/MATCH formula in col D works in all cases
https://www.dropbox.com/s/fe0sb6bkl3phqdr/vlookup.xls