I am creating a bookmarklet and the code below is not working on first try. When I goto a page, it says "jQuery is not defined". But, if I click it again, it works perfectly?

var qrcodetogo = {
jQURL: 'http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js',
jQUIURL: 'http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/jquery-ui.min.js',
jQUIThemeURL: 'http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/themes/ui-lightness/jquery-ui.css',
init: function(){
    this.createLink('qrcodetogo_UI-Lightness', this.jQUIThemeURL);
    this.createScript('qrcodetogo_jQuery', this.jQURL);
    this.createScript('qrcodetogo_jQueryUI', this.jQUIURL);
    this.createHiddenDiv('qrcodetogo_dialog','This is a Test.');
    jQuery.noConflict();
},

showQRCode: function() {
    jQuery('#qrcodetogo_dialog').dialog();
},

createLink: function(id, url) {
    var l = document.createElement('link');
    l.href = url;
    l.rel = 'stylesheet';
    l.type = 'text/css';
    l.media = 'screen';
    l.charset = 'utf-8';
    document.getElementsByTagName('head')[0].appendChild(l);
},

createScript: function(id, url) {
    var s = document.createElement('script');
    s.src = url;
    s.id = id;
    document.getElementsByTagName('head')[0].appendChild(s);
},

createHiddenDiv: function(id, body) {
    var div = document.createElement('div');
    div.id = id;
    div.innerHTML = body;
    div.style.display = 'none';
    document.getElementsByTagName('body')[0].appendChild(div)
}
}

qrcodetogo.init();
qrcodetogo.showQRCode();