I followed jQuery Datatable - Sliding child rows example (just look at \"Complete code\" section on that page) in my ASP.NET MVC project and I could listed master & stat
You need to show loading indicator in the child row, retrieve content via Ajax and inject it into the child row replacing loading indicator.
For example:
// ... skipped ...
// Open this row
row.child('<p><center>Loading...</center></p>', 'no-padding' ).show();
tr.addClass('shown');
$('div.slider', row.child()).slideDown();
$.getJSON("GetStudents?id=" + id, function(data){
$('td', row.child()).html(format(data));
$('div.slider', row.child()).show();
});
// ... skipped ...
See this example for code and demonstration.