Hello there, We setup API posting in safecart & did a test transaction. But it does not post back. Please give instructions how to do so!!
If I had access to your aMember CP, I would look at aMember Cp -> Logs -> Invoice Log and give you the exact response. Not sure how could we help you via forum. Please submit a ticket (or followup) to https://www.amember.com/support/ and we will resolve the problem with recently written, beta safecard plugin ASAP.