Submission that are incomplete

I see on jotform that 8 submission payments are incomplete.  I tried to do hit it manually; however, an error was detected.

I have not received payment notification for those either from PayPal.

Incomplete payments just mean that your users changed their mind in the last minute. Unless there is a glitch in the system. I would recommend you to enable IPN (Instant Payment notification) in your Paypal account to prevent this from happening

Here is more information about IPN

http://www.jotform.com/help/272-Paypal-Incomplete-Payments-FAQ

Here are some guides to help you to enable IPN

http://www.jotform.com/help/276-How-to-Enable-IPN-for-Paypal

http://www.jotform.com/help/279-How-to-Enable-IPN-for-Paypal-Pro