You typically will have very little success using validators and checkers against Liferay. It's code is right and will work, it just doesn't necessarily conform to the "best practices" promoted by these organizations.
They know all about static or servlet-based HTML pages, but they know little if any about portlets and the portlet namespacing of IDs in order to prevent form element collisions.
Some tools can't handle the additional javascript that runs in the browser after the page has loaded which updates the DOM. Don't know about your tool per se, but it's something to consider.
After looking at your page, it appears to be a standard portal page. If it renders correctly within your organization, that's often the best validation you can get.
