Simple Drupal Modal/Lightbox/Dialog task

I have a form in Drupal 7 which I want to open in a Dialog or modal window. - When user submits this form, if there is any error then the form is displayed back in the modal window with errors. - When the form is submitted, if there are no errors then the confirmation message should show in the dialog window as well. - This form should open when user clicks a link. I have tried ctools and diaplog API but I couldn't get it working properly but you can do it using any module as long as it works properly. I followed this article, [login to view URL] . For the purpose of tasks, you can have a form with two text fields. I need it to be done urgently as it should be a straight forward task for someone who has done this before. Please let me know if you have any questions. Thanks