<script>
    $(document).ready(function(){
        $("#demoForm").validate();
      });
        $.validator.messages.required = "Заполните поле!";
        $.validator.messages.email = "Неверный формат email";
       </script>    

 <form id="ajax-contact-form" method="get" action="">
			 <fieldset>
			    <div class="span-25 last" style="height: 60px;">
		                 <div class="span-8 form notopmargin">
				 <input name="name" size="25" placeholder="Name" class="required" maxlength="40" />
				 </div>
				 		 <div class="span-8 form notopmargin">
                 <input name="email" size="25" placeholder="Email"  class="required email" /></div>
			   </div>
					   
			   <div class="span-17 last notopmargin">
				
				<input name="dasdasd" size="25"  class="required" value="" placeholder="Subject"  maxlength="100" />
			   </div>
			   
			 <div class="span-17 last">
				 <textarea name="comment" rows="5" cols="25" placeholder="Message"  class="required" maxlength="4096"></textarea>
			   </div>
			   
			   
			   <div style="padding-top:20px">
				 <input type="submit" value="Send" style="margin-top:20px"/>
			   </div>
			 </fieldset>
		 </form>

но проверяет только почту и последнюю textarea, а name и subject остаются без проверки