parsererror for auto-complete search script

parsererror for auto-complete search script

i am writing an auto-complete function for a search box on my website and am facing a parsererror when i make an ajax request. i have a feeling it has to do with parsing the json. i am using the json_encode method in php, so i dont think there should be any trouble - regardless, would appreciate if you could help me debug --

code:
/* php script that is called to make a json array of possible search terms */
<?php
  if (strlen($_REQUEST['search-text']) < 1) {
    print '[{}]';
    exit;
  }
  $terms = array(
    'access',
    'action',
    'accumulate',
        'boston',
        'byte',
    'xaml',
    'xoops',
  );
  $possibilities = array();
  foreach ($terms as $term) {
    if (strpos($term, strtolower($_REQUEST['search-text'])) === 0) {
      $possibilities[] = $term;
    }
  }
  print json_encode($possibilities);
?>


SAMPLE OUTPUT for search-text = 'ac' is ["access","action","accumulate"]

/* javascript code that makes the ajax request */
        // suggestion list upon query
        var $autocomplete = $('<ul class="autocomplete"></ul>').hide().insertAfter('#search-text');
        $('#search-text').attr('autocomplete','off');
  $('#search-text').keyup(function() {
                $.ajax({
                        'url': 'jquery_search_autocomplete.php',
                        'data': {'search-text': $('#search-text').val()},
                        'dataType': 'json',
                        'type': 'POST',
                        'error': function (XMLHttpRequest, textStatus, errorThrown) {
                                $('<p></p>').text(textStatus).insertAfter('#search-text');
                        },
                        'success': function(data) {
                                if (data.length) {
                                        $autocomplete.empty();
                                        $.each(data, function(index, term) {
                                                $('<li></li>').text(term).appendTo($autocomplete).click(function() {
        $('#search-text').val(term);
        $autocomplete.hide();
      });
                                        });
                                        $autocomplete.show();
                                }
                        }
                });
  });


again, an error is being thrown upon the ajax request - errortext = parsererror

thanks in advance!