I'm currently checking for duplicate entries in a sheet by using data validation - =ISNA(VLOOKUP($C53,RANGE1,1,FALSE)), so that if a duplicate is entered, it brings up an error message.

What I want to do is extend this to include other ranges i.e. =ISNA(VLOOKUP($C53,RANGE1 RANGE2 RANGE3 etc,1,FALSE))

Is this possible? And if so, how? I've tried commas, semicolons, colons, but nothing seems to work.