VI Export Conditional Expression

Morning,

I am trying to create a conditional express for a VI export job, but don't seem to be able to figure out the formula. Can someone guide me on what it is I am doing wrong (if not all)? 

{SY_SalesTaxClass29.TaxClass$} = "NT"  then {Temp002$} = "Y" ELSE {Temp002$} = "N"

Thanks

RM