How to use named ranges in R1C1 notation?

Hi, I am encountering the following problem - I don`t seem to be able to use named range in R1C1 formula.
The formula

=IFERROR(VLOOKUP(RC[-15]&RC[-12]&RC[-6],named_range,8,FALSE),"")

The whole line

ActiveSheet.range("R" & planStartRow & ":R" & planEndrow).SpecialCells(xlCellTypeVisible).FormulaR1C1 = "=IFERROR(VLOOKUP(RC[-15]&RC[-12]&RC[-6],named_range,8;FALSE),"")"

This gives me Runtime error 1004.

Is there any way around this, or is it not possible to use named ranges in this way?