Show command

Show command

I'm new to jquery and I'm working an a little project, which is a simple login form.  I have a form inside a fieldset that contains 2 textboxes, Username and password and a submit buttion.. In the fieldset but outside the dorm a have a 'div' if the validation fails it prints a message about the failure.  It works but it just flashes on then goes away; Can anyone tele me what I'm doing wrong?
HTML Code:
  1. <fieldset class="ui-widget-content ui-corner-all"><legend class="ui-widget-header ui-corner-all">NFP User Login</legend>
       <div id="message"></div>
       <form class="ui-widget">
        <label for="username">Username:<span class="form-required" title="This field is required.">*</span></label>
        <input id="username" class="ui-widget-content ui-corner-all" type="text" name="username" />
        <label for="password" >Password:<span class="form-required" title="This field is required.">*</span></label>
        <input id="password" class="ui-widget-content ui-corner-all" type="password" name="username" />
        <div style="margin-top: 1em;">
        <span id="forgot"><a href="#">Forgot Password...</a></span>
        <span id="flogin" style="float:right; margin-right: .1em;">
         <button type="submit" id="login" name="Login"> Login </button>
        </span>
        </div>
       </form>
       <div id="loading">loading</div>
      </fieldset>














jquery code:
  1. $(document).ready(function() {
      $('#loading').hide();
      $('#message').hide();
      $('#username').focus();
      $('form').
      submit(function() {
       var error = false;
          $(this).find(":text").each(function() {
        if ($(this).val().length == 0) {
         //$('#message').hide();
         $('#message')
          .html("You must Enter a Username")
          .addClass('form-required')
          .show();
         $('#username').focus();
        }
       }); // end of find text
      
      }); // end of sublit
     }); // end doc ready