Quote Originally Posted by DrByte View Post
"Pending unilateral" means you specified an email address in your Zen Cart PayPal settings that doesn't match up to an existing PayPal account, and sent money to that address.
PayPal has set the transaction in a pending status waiting for you to reply to an email that they've sent you asking you to create a PayPal account for that address, or to add that address to an existing PayPal account ... before you can collect the funds that are waiting. If you don't respond within a certain number of days, they will refund the transaction automatically.

I have checked and re-checked that address and it is right, but in the paypal account the email address has not been confirmed, apparently. I am hoping this is the problem, and I am getting the client to confirm it right now.