Pardot inserting shortcode button not working

Hi,

Amazing I installed the pardot and after installation of username and passwork key.

I want to use the pardot in my page when I click on pardot icon to insert the shortcode in page then a blank lightbox open and in lightbox i cannot see any thing.

Further investigate I found only this problem in red color in firebug.
“NetworkError: 500 Internal Server Error – http://dev.qsdigitalsolutions.com/wp-content/plugins/pardot/js/tinymce/pardot-forms-shortcode-popup.php”

Although specially check the directly for confirmation of file exist. then file is available.

I am stuck so I have buy the pardot but unlucky.

https://wordpress.org/plugins/pardot/