Flask not working on Abyss Server

I have made a Flask application which I am trying to put on Abyss Web Server. I have followed the instructions given by the server however it is returning a 500 'Internal Server Error' error when I try to access the page. The app definitely works when I use the inbuilt testing server but I can't get it working on the Abyss Web Server.

I am using the cpython Python installation not ActivePython as Aprelium recommend

I tired using a virtual python installation with the .py file in a sub-folder but it has not worked. How can I get it working?

Thanks in advance.