I have setup sandbox buyer/seller accounts, and setup the API uname/pwd/sign on my nopcommerce site, and I can succesfully purchase an item from the nopcommerce store.
But, when I tryo to setup this using live paypal, I can complete anorder, I receive the error,
"LongMessage: This transaction cannot be processed due to an invalid merchant configuration. ShortMessage: Invalid Configuration ErrorCode: 10501 "
Any suggestions?