Paypal Payment Error

I installed the camptix plugin and setup a ticket. When trying to process a payment I get the error: A payment error has occurred, looks like chosen payment method is not responding. Please try again later.

I installed the Core Control plugin and ran the logger which told me I had a problem with the SSL certificate: http_request_failed SSL certificate problem, verify that the CA cert is OK. Details: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed.

Turns out I didn’t have a certificate installed. So I installed a certificate, deleted the plugin and reinstalled it. But when I tried to register I got the same message: A payment error has occurred, looks like chosen payment method is not responding. Please try again later.

so I am still stuck. Please guide me on to the next steps to take.Thanks.

http://wordpress.org/extend/plugins/camptix/