This works

function onEdit(e) {

var triggerCell = 'A14';

var incrementCell = 'a12';

var ss = SpreadsheetApp.getActiveSpreadsheet();

var editedCell = ss.getRange("a14")

if (editedCell.getA1Notation() === triggerCell) {

var currentValue = ss.getRange(incrementCell).getValue();

var newValue = currentValue + 1;

ss.getRange(incrementCell).setValue(newValue);

} }