excel formula in qlikview

[inam]

Hello Community

I need this Excel  formula in QlikView. 

excel formula :-    =IFERROR(1/COUNTIF([File No.],[@[File No.]]),0)

I am trying  this IF(COUNT([File No.]) > 0, 1 / COUNT({< [File No.] = {"$(= [File No.])"} >}), 0)  in script(backend)But its show error.

how I use this excel formula in Expression also( front end) .