表单永远不会使用jQuery验证插件提交-即使有效

我正在使用jQuery验证插件来验证我的表单，但是即使成功验证后，该表单也不会提交.这是重现此问题的代码:

I am using a jQuery Validation plugin to validate my form, but the form does not submit even after successful validation. Here is code to reproduce the issue:

<?php
if(isset($_REQUEST['submit'])){
    echo "form submitted";  //have to insert into database here
}
?>

<script src="http://code.jquery.com/jquery-latest.js"></script>
<script type="text/javascript" src="http://jzaefferer.github.com/jquery-validation/jquery.validate.js"></script>
<script type="text/javascript">
jQuery.validator.setDefaults({
    debug: true,
    success: "valid"
});;
</script>
<script>
  $(document).ready(function(){
    $("#myform").validate({
  rules: {
    field1: {
      required: true,
      number: true
    },
    field2: {
      required: true,
      number: true,
      minlength: 3
    },
    field3: {
      required: true,
      email: true
    }
  }
});
  });
  </script>


    <form id="myform" method="post" action="">
      <div>
        <label for="field">Required, decimal number: </label>
        <input class="left" id="field1" name="field1" type="text" />
      </div>
      <br>
      <div>
        <label for="field">Required, Minimum length 3: </label>
        <input class="left" id="field2" name="field2" type="text" />
      </div>
      <br>
      <div>
        <label for="field">Required, email: </label>
        <input class="left" id="field3" name="field3" type="text" />
      </div>
      <br/>
      <input type="submit" name="submit" value="Validate!" />
    </form>

请注意，无论是否在表单标签中执行有效操作，都会发生这种情况.

Note, this happens with or without a valid action in the form tag.

这可能是什么原因造成的?

What could be causing this?