I ran into the same error. In my case, I missed the "NOTE: under "Step 5
- Create the Publication Template". It reads: The DOM interface option
is checked by default and this means that this document will not be
accessible if you use the E4X syntax. The DOM interface must be used
when this option is checked and is the recommended syntax.You can still
use the E4X syntax. If so, make sure to uncheck this option.The E4X
syntax is what allows you to access the properties directly (e.g. <%=
content.@...