CGI Proxy hotlink protection not working

If my hotlink protection worked properly, the above image would not load.

For some reason, my CGI hotlink protection isn't working. Below is the code I put in my .htaccess. Can anyone help me get it working properly?

RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !thunderunblock\.info [NC]
RewriteRule ^nph-proxy.pl.(.+)$ /index.php? [R]

Code (markup):

Thanks for the help!

 

If you have cPanel, it must be available there.

Would you be able to try through that?