I am an absolute newbie trying to get started using SIM and have defined a Silent Post URL.  This URL is getting invoked when I have a successful authorization performed.  As an experiment, though,  I entered a correct credit card number but an invalid 3-digit security code.  Authorize.net responded with a 'transaction declined' message to the browser and I was not allowed to retry with a new security code (I got a duplicate transaction error when I tried).  However, my Silent Post URL was never posted to for this decined transaction.

I was under the impression that even declines are posted to the Silent Post URL and my processing logic depends on this happening..  Have I misunderstood  how this is supposed to work or is there a system problem?