=IF(ISERROR(VLOOKUP(A3,contacts!B:I,5,FALSE)), " ",

VLOOKUP(A3,contacts!B:I,5,FALSE))

Vlookup never result blank when the lookup value is present in the lookup

range. It will result 0 value when the resulting column is not having any

value.

I think you are looking for a formula like the below:-

=IF(ISNA(VLOOKUP(A3,Contacts!B:I,5,FALSE)),"Lookup Value is not Available in

The Lookup Range",VLOOKUP(A3,Contacts!B:I,5,FALSE))

If you want to show the Display message as BLANK when the lookup value is

not present in Lookup range then use the below one:-

=IF(ISNA(VLOOKUP(A3,Contacts!B:I,5,FALSE)),"BLANK",VLOOKUP(A3,Contacts!B:I,5,FALSE))

Instead of using ISERROR use ISNA.

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