Async upload problem using jquery.form.js

I'm using the jquery.form plugin to asynchronously upload documents in an MVC project.

Taking my lead from this previous answer, here's what I have on the page:

<% using(Html.BeginForm("Create", "JobFile", FormMethod.Post, new { id = "uploadForm", enctype = "multipart/form-data" })) %>
<% { %>
<%: Html.ValidationSummary() %>

    <input type="file" id="fileToUpload" />
    <input type="submit" value="Upload file" />
    <input type="text" id="RelatedFileName" />

<% } %>

<script type="text/javascript" src="../../Scripts/jquery-1.4.1.min.js"></script>
<script type="text/javascript" src="../../Scripts/jquery.form.js"></script>
<script type="text/javascript">
    $(function () {
        $('#uploadForm').ajaxForm(function (result) {
            if (result.errorMessage != '') {
                alert(result.errorMessage);
            } else {
                $('#RelatedFileName').val(result.fileName);
            }
        });
    });
</script>

My problem is that when the page loads I get the 开发者_运维知识库following javascript error:

Uncaught TypeError: Object # has no method 'ajaxForm'

This error is found on the line containing

$('#uploadForm').ajaxForm(function (result) {

Can anyone tell me why I'm getting this error?

Check that jquery isn't being included in the page twice.

Here is the method that I am using for MVC3, CodeIgniter and Yii. One important this is that your should specify method="post", enctype and encoding="multipart/form-data"

var submitForm = function(_formId){
var _genMsg = $('#genMsg');
_submitForm = $('form').index($('#'+_formId));
if(subCommonForm(_submitForm, 'main')){
    _genMsg.attr('class', 'information-box round');
    _genMsg.html('Saving...');
    $('#'+_formId).ajaxForm({
        dataType: 'json',
        success: function (data) {
            _genMsg.attr('class', 'information-box round');

            data.code == 0
                ? _genMsg.attr('class', 'confirmation-box round')
                : _genMsg.attr('class', 'error-box round');

            _genMsg.html(data.message);
            _genMsg.fadeIn();
        }
    });

    $('#'+_formId).submit();
}
};

Is 'uploadForm' the id of your <form> object? If it is then you may wan to check in something like FireBug to make sure your plug-in is included on your page properly.

The shortcut:

$(function () {

Doesn't work in latest version of jQuery, have to use:

 $(document).ready(function () {

check if you have the $

$('#your-form')

and not

('#your-form')