Why is my Simple Recorded Macro not working?

Hi everyone,

I have recorded a macro to input a formula and drag down to get results for a whole table. Really simple.

This is what I wrote:

Sub NotWorking()
'
' Macro14 Macro
' Macro recorded 27/08/2013 by hughesa
'

'
    ActiveCell.FormulaR1C1 = _
        "=IF(ISERROR(INDEX(R4C12:R47C12,MATCH(LEFT(R[-1]C[-5],13),R4C10:R47C10,0))),"""",INDEX(R4C12:R47C12,MATCH(LEFT(R[-1]C[-5],13),R4C10:R47C10,0)))"
    Range("F5").Select
    Selection.FillDown
    Selection.End(xlUp).Select
End Sub

When I run this macro, why does nothing occur on the screen? viz a viz, no formulas appear where they are intended to be.

See attached workbook: To see what I'm on about, on open sheet, run macro "NotWorking"

Any help would be greatly appreciated!

Andrew