nested $.each doesn't work in IE8

nested $.each doesn't work in IE8

Hi,
I've got a strange problem:
with an object like
  1. {"level1":[{"values":{"level2":"valuelevel2","level2a":"valuelevel2a"},"index":"index1"},{"values":{"level2":"valuelevel2","level2a":"valuelevel2a"},"index":"index1"}]}
 if I want to use a nested jquery each, IE8 prints only one 'ok' running this code [reporting an error]:

  1. $.each(result, function(i, result_wrapper){
  2.         $.each(result_wrapper, function(i, result_values){
  3.             if(result_values["index"] == 'index1' ) {
  4.                 document.write("ok");
  5.             } else {
  6.                 document.write("ko");
  7.             }
  8.         });
  9.     });

This works with FF and Chrome.
Why? Is there a workaround?

   Thanks in advance