email - PHP can't find class 'GhostMailer'

So i am trying to call some functions of a mailer class.. In phpStorm when i typeGhostMailer::setSender();

I can navigate to the file when i click my scroll button on theGhostMailer:: text to where GhostMailer is into, but whenever i run the program it says class GhostMailer not found..

Code for calling

GhostMailer::setSender(Input::get('emailfrom'));
GhostMailer::addRecipient(Input::get('emailto'));
GhostMailer::setSubject(Input::get('subject'));
GhostMailer::setHTML(true);
GhostMailer::setMessage(Input::get('email'));
GhostMailer::setReturnAddress(Input::get('emailfrom'));
GhostMailer::getHeaders();
GhostMailer::send();
Copy code

How do i fix this?