Thank you for your reply,

I have put the below into the spreadsheet and got the {} around the formula, but it is still coming up with zeros...

=IFERROR(INDEX(Sheet1!$A$2:$A$800,MATCH(0,IF(ISBLANK(Sheet1!$A$2:$A$800),"",COUNTIF(B$3:$B3,Sheet1!$A$2:$A$800)),0)),"")

Not sure if i made an error somewhere