Not working after install in Joomla

I have install the tree files on the website of chronoengine.com in joomla BE
When i wil start the Chronoform validation screen it wil give a error
Http 500. no other options wil work. Installation was oke.
What can i do to make it works

Ria

Hi Ria,

What is Joomla! BE? (Back End?)

Please make sure that you have the installed the correct version of ChronoForms for the Joomla! version you are using. That is the most common cause of this kind of error.

Bob