Problem with the vlookup function

[RomainChaize]

Hello everyone! I have a problem with the VLOOKUP function in excel.
My objective is to retrieve information from the "Customers" sheet based on the contents of column A of this first sheet.
Here's the formula I use : =IFERROR(VLOOKUP(A1,Clients!B:A,1,FALSE),"")

The result is always #NAME?. 

Thank you for your time 😊

[#2]

@RomainChaize 

Your description mentions Customers but the formula has Clients.

Also, in which column do you want to look up the value of A1, and from which column do you want to return the corresponding value?