Error after install PayPal module

[bircastri]

I installed PayPal module on my prestashop site (prestashop 1.5) but, after that I receive this error and I m not able to remove it from console the error is this:

 

Warning: require(/web/htdocs/www.safarino.it/home/modules/paypal/backward_compatibility/backward.php): failed to open stream: No such file or directory in /web/htdocs/www.safarino.it/home/modules/paypal/paypal.php on line 127 Warning: require(/web/htdocs/www.safarino.it/home/modules/paypal/backward_compatibility/backward.php): failed to open stream: No such file or directory in /web/htdocs/www.safarino.it/home/modules/paypal/paypal.php on line 127 Fatal error: require(): Failed opening required '/web/htdocs/www.safarino.it/home/modules/paypal/backward_compatibility/backward.php' (include_path='.:/php5.6/lib/php/') in /web/htdocs/www.safarino.it/home/modules/paypal/paypal.php on line 127

How can I fixed it?