Won't run ajax if I change input type..?

I have a form for user to update their info using jquery + Ajax. Everything is working great so far, but WHen i change input type="email" to input type="text" in the fullname section of the form and click update. It got error??? It won't run the php file in ajax. I don't see any connection which causes this error? Anyone please sugguest why? But if I change input type in the fullname section back to "email". It works! This is so weird!

Here is my form:

 <div id="changeuserinfo_result"></div>
    <form role="form" method="post">
                <div class="form-group">
                <label>Fullname</label>
                <input type="text" class="form-control" id="changename" name="changename" value="<?php echo $_SESSION['name'] ?>">
                </div>
                <div class="form-group">
                <label>Password</label>
                <input type="password" class="form-control" id="changepass" name="changepass" value="<?php echo $_SESSION['pass'] ?>">
                </div>
                <button class="btn btn-default" id="changeuserinfo">Update</button>
                </form>

Here is my jquery code:

$(document).ready(function(){
$('#changename').focus();  
$('#changeuserinfo').click(function(){ 
    var changename = $('#changename');  
    var changepass = $('#changepass');
    var changeuserinfo_result = $('#changeuserinfo_result'); 
    changeuserinfo_result.html('loading...');
    if(changename.val() == ''){ 
        changename.focus();
        changeuserinfo_result.html('<span class="errorss"> * Empty fullname</span>');
        return false;
    }
    else if(changepass.val() == ''){ 
        changepass.focus();
        changeuserinfo_result.html('<span class="errorss">* Empty password</span>');
        return false;
    }
    else {
        var UrlToPass = {changename:changename.val(),changepass:changepass.val()} ;
        $.ajax({ 
        type : 'POST',
        cache: false,
        data : UrlToPass,
        url  : 'changeuserinfo.php',
            success: function(responseText){ 
                if(responseText == 1){
                    $('#changeuserinfo_result').html('<span style="color:green"> Update OK</span>');
                }
                else{
                    $('#changeuserinfo_result').html('<span class="errorss"> Update fail. Try again</span>');
                }
            }
        });
    }
});
});