Have reviewed your install. Your entire installation is massively out of date. CBSubs itself is 8 months out of date. At the very least please update CB, CBSubs, and any CB plugins.
Regarding your PayPal gateway settings I recommend adjusting the following as well.
PayPal Business (email or secure merchant ID): This should be set to merchant id
PayPal Main receiver account (email) (if Business is different from your main account): This should be set to whatever email address is marked as primary within your PayPal account
Your PayPal Identity Token: Please be sure this is absolutely correct as it seams far too short to be a PayPal token
See the below URLs where you can find the above information. It seams like your gateway isn't configured properly.
Merchant ID:
Code:
https://www.paypal.com/myaccount/settings/
Identity Token:
Code:
https://www.paypal.com/businessmanage/preferences/website
IPNS:
Code:
https://www.paypal.com/merchantnotification/ipn/preference