Extracting unique items from a named range getting duplicates

[pujo]

Extracting unique values from a named range using an array formula.
For some reason, I keep getting duplicate values. I've ensured the duplicate values in the list are exactly the same to avoid the possibility
of displaying duplicate due to extra spaces, and or different spellings. Pulling my hair out!

Anyone have any ideas?
Thanks!

{=INDEX(VendorCompany,MATCH(0,COUNTIF(Vendor!$A$1:A1,VendorCompany),0))}

 

[Domenic]

Did you enter the formula in Vendor!A2, confirm with CONTROL+SHIFT+ENTER, and copy the formula down the column?