Google apps sheets problem with auto id on a form

I have a auto generated sheet from google forms unfortuantely I am unable to make my formula for generating an id for all equipment in cell N2 work I have a auto script for adding nrs running Form [login to view URL] Formula in N2 =arrayformula( if( len(A2:A), "IT" & text(row(A2:A) - row(A2) + 1, "000"), iferror(1/0) ) ) Script running every time a entry changes function myFunction() { var AUTOINC_COLUMN = 0; var HEADER_ROW_COUNT = 1; var spreadsheet = [login to view URL](); var worksheet = [login to view URL]("Sheet1"); var rows = [login to view URL]().getNumRows(); var vals = [login to view URL](1, 1, rows+1, 2); for (var row = HEADER_ROW_COUNT; row < [login to view URL]; row++) { try { var id = vals[row][AUTOINC_COLUMN]; [login to view URL](id);[login to view URL]((""+id).length ===0); if ((""+id).length === 0) { // Here the columns & rows are 1-indexed [login to view URL](row+1, AUTOINC_COLUMN+1).setValue(row); } } catch(ex) { // Keep calm and carry on } } } I need someone familiar with google forms to help me make this function work