setDataValidation in google script not working

Question

Have a problem with setting data validation rules in a google spreadsheet using apps script. Below are two functions, one is an onChange function which will be triggered whenever a user changes the spreadsheet in any way.

The updatenamedataVal() function will be triggered whenever adds/removes a row from a specific sheet.

Everything works fine and the code executes. But there is no data validation set in the cells! Whats wrong?

function myonChange(e){
  var ss = e.source.getActiveSheet();
  var ssname = ss.getSheetName();
  if((e.changeType === 'INSERT_COLUMN' || e.changeType === 'REMOVE_COLUMN') && ssname !== 'Aggregates'){
    Browser.msgBox('Whoops!','You are not allowed to add/remove columns. Please undo action by pressing CTRL+Z', Browser.Buttons.OK);  
  }
  else if((e.changeType === 'INSERT_ROW' || e.changeType === 'REMOVE_ROW') && ssname === 'Teacher Details'){
    var ssrange = ss.getDataRange();
    var valrange = ss.getRange(2,3,ssrange.getLastRow(),1);
    updatenamecelldataVal(valrange);
  } 
};


function updatenamecelldataVal(valrange){
      var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets();
      var numsheets = SpreadsheetApp.getActiveSpreadsheet().getNumSheets();
      var rule = SpreadsheetApp.newDataValidation().requireValueInRange(valrange).build();
      for(var i = 0; i < numsheets; i++){
        var sheetname = sheets[i].getName();
        var sheetrange = sheets[i].getDataRange();
        var sheetlastrow = sheetrange.getLastRow();
        if(sheetname !== 'Teacher Details' && sheetname !== 'Aggregates' && sheetname !== 'List of Subjects'){
          for(var j = 0; j < (sheetlastrow/17); j++){
            var namecell = sheetrange.getCell(4+(17*j), 2);
            namecell.clearDataValidations();
            namecell.setDataValidation(rule); 
          }
        }
      }
    }; 

Answer 1

The following code works as expected, in row 4, column 2 set the data validation in the cell. I changed some lines to adjust my test environment.

/*
In the Spreadsheet, create new trigger:
Run: onChange
Events: From spreadsheet
On change
*/

function onChange(e) {
  var ss = e.source, valrange;
  var s = ss.getActiveSheet();
  var sname = s.getSheetName();
  if((e.changeType === 'INSERT_COLUMN' || e.changeType === 'REMOVE_COLUMN') && sname !== 'Aggregates')
    Browser.msgBox('Whoops!','You are not allowed to add/remove columns. Please undo action by pressing CTRL+Z', Browser.Buttons.OK);  
  else if((e.changeType === 'INSERT_ROW' || e.changeType === 'REMOVE_ROW') && sname === 'Teacher Details') {
    valrange = s.getRange(2, 3, s.getDataRange().getLastRow() - 1, 1);
    updatenamecelldataVal(valrange, ss);
  }
}

function updatenamecelldataVal(valrange, ss) {
  var sheets = ss.getSheets(), namecell;
  var numsheets = sheets.length; //SpreadsheetApp.getActiveSpreadsheet().getNumSheets();
  var rule = SpreadsheetApp.newDataValidation().requireValueInRange(valrange).build();
  for(var i = 0; i < numsheets; i++) {
    var sheetname = sheets[i].getName();
    var sheetrange = sheets[i].getDataRange();
    var sheetlastrow = 17; //sheetrange.getLastRow();
    if(sheetname !== 'Teacher Details' && sheetname !== 'Aggregates' && sheetname !== 'List of Subjects') {
      for(var j = 0, len = sheetlastrow / 17; j < len; j++) {
        namecell = sheetrange.getCell(4 + (17 * j), 2);
        namecell.clearDataValidations();
        namecell.setDataValidation(rule); 
      }
    }
  }
}

Answer 2

Here's a simpler version of wchiquito's script which I had problems with. It doesn't precisely match the questioner's code but should be simpler to understand and adapt:

function onChange(e) {

  var ss = e.source, valrange;
  var s = ss.getActiveSheet();
  var sname = s.getSheetName();

  if((e.changeType === 'INSERT_ROW' || e.changeType === 'REMOVE_ROW') && sname === 'Accounts') {
    valrange = s.getRange(2, 1, s.getMaxRows()-1, 1);
    updatenamecelldataVal(valrange, ss);
  }
}

function updatenamecelldataVal(valrange, ss) {
  var sheets = ss.getSheets();
  var targetCells;
  var rule = SpreadsheetApp.newDataValidation().requireValueInRange(valrange).build();
  for(var i = 0; i <= sheets.length; i++) {
    var sheetname = sheets[i].getName();
    if (sheetname !== 'Accounts') {
      targetCells = sheets[i].getRange(2, 1, sheets[i].getMaxRows(), 1);
      targetCells.clearDataValidations();
      targetCells.setDataValidation(rule);
    }
  }
}