Symfony sfFormExtraPlugin ajax error

Question

I'm getting this error in Firefox javascript console. Does it mean jQuery UI is badly configured or is it programming error, e.g. bad values returned by ajax symfony action?

I'm using sfFormExtraPlugin plugin's DoctrineAutocompleter... or trying to use it.

Error: jQuery("#autocomplete_table1_table2").autocomplete("http://myurl/frontend_dev.php/model/ajax", jQuery.extend({}, {dataType: "json", parse: function (data) {var parsed = [];for (key in data) {parsed[parsed.length] = {data: [data[key], key], value: data[key], result: data[key]};}return parsed;}}, {})).result is not a function Source File: http://myurl/frontend_dev.php/model/action Line: 104

Thanks in advance...

Edit: here is the code generated by symfony:

jQuery(document).ready(function() {
    jQuery("#field_id")
    .autocomplete('/frontend_dev.php/module/ajax', jQuery.extend({}, {
      dataType: 'json',
      parse:    function(data) {
        var parsed = [];
        for (key in data) {
          parsed[parsed.length] = { data: [ data[key], key ], value: data[key], result: data[key] };
        }
        return parsed;
      }
    }, { }))
    .result(function(event, data) { jQuery("#field_id").val(data[1]); });
  });