The code change that Willi posted will fix the issue you are having.
To say that we do not offer support for our software is not quite accurate. We offer support for our software right here in these forums.
If you end up end up having problems using eCart, please post your question to the eCart forum and we will help you out, usually within 24 hours of your question being posted. If it turns out to be something we cannot help you with through the forums, we will start an incident and contact you by phone.
If you are not happy with the documentation, please send your comments to the documentation team using our feedback form:
feedback.php?type=docs