Thanks, glad you like it.

Let's see, it looks like curl_exec is returning FALSE here, which means it failed. Otherwise it would return XML data to parse. We should implement some error handling to support that, so you don't get the blank screen, but that doesn't solve why your curl_exec is failing. I've never had it return false on me...

Does it happen every time? Does the rest of the module work (checkout, editing cards, etc)?

To debug this further, I think we'd have to see more of what curl is doing. In function uc_cim_curl_send($content), if you change curl_setopt($ch, CURLOPT_HEADER, 0) to curl_setopt($ch, CURLOPT_HEADER, 1) and tell me what the raw output of curl_exec($ch) is, we should be able to see why it's failing. Let me know if you need help with this.

Best
Chad