Something wrong with my ajax return false

Something wrong with my ajax return false

Hi, I'm beginner in Javascript and Ajax. In this code below I have two validations in my form. The first part checks via ajax if the entered data already exist in the database. If not exist then everything is ok and return is true and script execute to the end (third part). But if return is false I've got this alert as I want, but I want to stop script right there. I don't want to execute script to the end (third part). Second part of form validation works fine. Please, help, where am I doing mistake?

  1. $('body').delegate('#gridder_addrecord', 'click', function(){
  2.          // First part : Do ajax  insert validation here
  3.          $.ajax({
  4.          url: "
  5.          
  6.             check_date_range.php
  7.          
  8.          ",
  9.          type: "POST",
  10.          data: 'date_from='+$('#date_from').val()+'&date_to='+$('#date_to').val(),
  11.          success: function(response){
  12.          if(response > 0){
  13.          $('#date_from').focus();
  14.          alert('Check your dates!!!');
  15.          return false;
  16.          }
  17.          }
  18.          });
  19.          // Second part: Do insert validation here
  20.          if($('#season').val() == '') {
  21.          $('#season').focus();
  22.          alert('Nedostaje naziv perioda');
  23.          return false;
  24.          }
  25.          // Third PaArt: Pass the form data to the ajax page
  26.          var data = $('#gridder_addform').serialize();
  27.          $.ajax({
  28.          url : '
  29.          
  30.             ajax.php?last_id=<?php
  31.          
  32.          ho $_GET['last_id']; ?>',
  33.          type : 'POST',
  34.          data : data,
  35.          success: function() {
  36.          LoadGrid();
  37.          }
  38.          });
  39.          return false;
  40.          });