iserror help

[Scott@CW]

Can someone please help with turning the below formula into an iserror. I
have tried several times but keep getting a format error.

IF(VLOOKUP(--H21,$B$21:$B$200,1,FALSE),"No","Yes")

Thank you.

 

[JE McGimpsey]

Not sure what "turning (the) formula into an iserror" really means, but
perhaps:

=IF(ISNA(MATCH(--H21,$B$21:$B$200,FALSE)),"Yes","No")

or

=IF(COUNTIF($B$21:$B$200,--H21)>0,"No","Yes")