I understand - it was simply a generic error message box saying the xml file failed to generate.
Interestingly, I reinstalled the script and restarted DOpus. I just tried to generate the message for a screen shot and the script worked again, mysteriously.
Glad to hear it works fine again.
If it was to fail again, do not hesitate to take a screenshot of the error, and also have a look at (and copy/paste) the script logs.