this topic has so many posts.

i'm having a similar problem as others.

I've got GCO sandbox setup on my shop, and I can click it and checkout. The orders are shown in my GCO account orders section, however nothing appears in ZC. My response_error and response_message logs are blank. Just out of curiosity, at the top of response_handler.php, I wrote some code to write a timestamp to a 3rd file. The 3rd file get written to when I directly to the response handler URL, but it never gets written to when I check out through GCO. I have set the API callback URL to the http://www.sss.com/googlecheckout/response_handler.php file on my site, and the callback method is XML.

I don't know what else to do or try, since it seems GCO will not even attempt to do any thing w/ myu response handler file. (as shown by no timestampe being written to the 3rd file).