[jQuery] ajaxForm returns error in IE7

[jQuery] ajaxForm returns error in IE7


I am using ajaxForm to upload an excel file and then display whether
or not it uploaded successfully. The following jQuery code works fine
in Firefox, but when I try to run it in IE7 it fails. The beforeSubmit
function is executed but then it craps out after that with the
following error: "Object doesn't support this property or method." The
form is generated dynamically, hence the reason for livequery.
$("#taskplans form.upload-form").livequery(function() {
    var h3 = $("#taskplans h3");
    var content = $("#taskplans div.content");
    $(this).ajaxForm({
        beforeSubmit: function() {
            h3.append(" " + loaderImg);
        },
        error: function(data) {
            h3.find("img").remove();
            content.html(data);
        },
        success: function(data) {
            h3.find("img").remove();
            content.html(data);
        }
    });
});