I have a register.php and a register.js I am checking in a sql database to see if the username and or the e-mail address is used. the script below work if I use one at a time
$(document).ready(function(){ $("#username").change(function() {
or $(document).ready(function(){$("#email").change(function() {


but if I try to check both only the e-mail will work.


part of the register.php
Code:
<div class="form_row">
                	<div class="row_label">Email
                    </div>
                    <div class="row_field">
                    	<input type="text" name="email" id="email" onkeyup="document.getElementById('twitter.updateemail').innerHTML = this.value;" class="text_box" />
                    <br><span id="twitter.updateemail" style="color:#006600; font-weight:bold;">EMAIL</span>
			<br><div id="status1"></div>
</div>
                </div>
                 <div class="form_row">
                	<div class="row_label">User Name
                    </div>
                    <div class="row_field">
			<input type="text" name="username" id="username" onkeyup="document.getElementById('twitter.updateUrl').innerHTML = this.value;" class="text_box"/>
			<br><span id="twitter.updateUrl" style="color:#006600; font-weight:bold;">USERNAME</span>
			<br><div id="status"></div>
		</div>
	</div>

register.js

Code:
/* Register */
$(document).ready(function() {
	$("#submitForm").validate({
		rules: {
			first_name: {
				required: true				
			},
			last_name: {
				required: true				
			},
			email:{
				required: true,
				email: true
			
			},
			username:{
			required: true,
			minlength:5

			}
			,
			password:{
			required: true
			},
			cpassword:
			{
				required: true,
				equalTo:'#password'
			}
			,
			website: {
				required: false,
				url: true
			
			},
			birth_date: {
				required: false,
				date: true
			
			},
			phnumber: {
				required: false,
				number: true
			
			},
			security_code: {
				required: true,
				equalTo: "#captchacode"
			}
							
		},	
		messages: {
			first_name: {
				required: 'Please Enter First Name!'
			},
			last_name: {
				required: 'Please Enter Last Name!'
			},
			email: {
				required: 'Please Enter Email Address!',
				email: 'Please Enter Valid Email Address'
			},
			username: {
				required: 'Please Enter UserName!',
				minlength: 'Please Enter UserName(Min 5 letters)'
			},
			password: {
				required: 'Please Enter Password!'
				
			},
			cpassword: {
				required: 'Please Enter Confirm Password!',
				equalTo: 'Please Enter Password Again'
			},
			website: {
				required: 'Please Enter Website Address!',
				url: 'Please Enter Valid URL'
			},
			birth_date: {
				required: 'Please Enter Birthdate!',
				date: 'Please Enter Correct Birthdate'
			}
			,
			phnumber: {
				required: 'Please Enter number!',
				number: 'Please Enter only Digits'
			},
			security_code:
			{
			  required: 'Please Enter the code Only Numbers!'
			}
		}		
	});

});


pic1 = new Image(16, 16); 
pic1.src = "images/loader.gif";

$(document).ready(function(){

$("#email").change(function() { 

var ema = $("#email").val();

if(ema.length >= 5)
{
$("#status1").html('<img src="images/loader.gif" align="absmiddle">&nbsp;Checking availability...');

    $.ajax({  
    type: "POST",  
    url: "includes/checkemail.php",  
    data: "email="+ ema,  
    success: function(msg){  
   
   $("#status1").ajaxComplete(function(event, request, settings){ 

	if(msg == 'OK')
	{ 
        $("#email").removeClass('object_error'); // if necessary
		$("#email").addClass("object_ok");
		$(this).html('&nbsp;<img src="images/accepted.png" align="absmiddle"> <font color="Green"> Available </font>  ');
	
}  
	else  
	{  
		$("#email").removeClass('object_ok'); // if necessary
		$("#email").addClass("object_error");
		$(this).html(msg);
	}  
   
   });

 } 
   
  }); 

}
else
	{
	$("#status1").html('<font color="red"><strong>Try Again</strong></font>');
	$("#email").removeClass('object_ok'); // if necessary
	$("#email").addClass("object_error");
	}

});

});

$( function () {
        
  twitter.updateemail();
  $('#email').focus();

      });

$(document).ready(function(){

$("#username").change(function() { 

var usr = $("#username").val();

if(usr.length >= 5)
{
$("#status").html('<img src="images/loader.gif" align="absmiddle">&nbsp;Checking availability...');

    $.ajax({  
    type: "POST",  
    url: "includes/check.php",  
    data: "username="+ usr,  
    success: function(msg){  
   
   $("#status").ajaxComplete(function(event, request, settings){ 

	if(msg == 'OK')
	{ 
        $("#username").removeClass('object_error'); // if necessary
		$("#username").addClass("object_ok");
		$(this).html('&nbsp;<img src="images/accepted.png" align="absmiddle"> <font color="Green"> Available </font>  ');
	
}  
	else  
	{  
		$("#username").removeClass('object_ok'); // if necessary
		$("#username").addClass("object_error");
		$(this).html(msg);
	}  
   
   });

 } 
   
  }); 

}
else
	{
	$("#status").html('<font color="red"><strong>Try Again</strong></font>');
	$("#username").removeClass('object_ok'); // if necessary
	$("#username").addClass("object_error");
	}

});

});


      $( function () {
        
  twitter.screenNameKeyUp();
  $('#user_screen_name').focus();

      });

thanks in advance for any help