We have problems with checkout and payment in Paypal normal, paypal express and credit card. the Problem can not be forced and is just sometimes. i need a real expert in Paypal API and php and sessions. the job is to observe the problem and solve it. In attachment i sent on screenshot of the error comes when payment not proccede the right way.
i understand perfect what do you want and i work something similar for another client.
will be a great task for my first experience on freelancer.com
thanks