Kobra,

The blank page tutorial:

Blank page
https://www.zen-cart.com/tutorials/index.php?article=82

was spot on. In it I read a typical problem was:

3. Common customization errors
The most common customization errors include:
  • using ' or " marks inside define() statements, resulting in matched quotes
  • removing or adding punctuation to define() statements, thus breaking the correct syntax. A define() statement should look like this: define('CONSTANT_NAME', 'value here');
  • missing semi-colons and periods, unbalanced parentheses, braces, brackets
  • uploading files to the wrong places. For more information about overrides, see the Overrides Chart and the Overrides FAQs


That last item is the likely culprit. I will be much more conscientious in the future about making changes.

Thanks again, Sean