Google Apps Script - simple onformsubmit

//Test function for Google Apps Script onFormSubmit
//Two sheets in a single spreadsheet doc
//First sheet corresponds to form
//Second sheet just displays one of the elements from the most recent form submission
// the function testOnSub() has a trigger associated with it: 'From spreadsheet' 'On form submit'
function testOnSub() {
  var ss = SpreadsheetApp.openById(SPREADSHEET_KEY);
  var sheet=ss.getSheets()[1];
  var form=ss.getSheets()[0];
  var lr=form.getLastRow();
  var el=form.getRange(lr,2,1,1).getValue();
  var t=el;//"done";
  sheet.getRange(1,1,1,1).setValue(t);
  
}​