Generating datatables child (more detail) row: “Uncaught TypeError: undefined is not a function ”
Generating datatables child (more detail) row: “Uncaught TypeError: undefined is not a function ”

'm trying to generate child rows as per the instructions here:
http://www.datatables.net/examples/api/row_details.html
The Datatable is doing exactly what it's supposed to, all the data is there, it's filtering and sorting properly. But when I trigger the event listener, I get an error at this line:
var row = table.row(tr);
Specific error: Uncaught TypeError: undefined is not a function.
Any ideas? I've trawled the documentation and cannot see where the problem is.
My code is as follows: