Set variable in Chrome extension failed for unknown reason

Question

I try to set up a small extension and thought I did everything right, but I'm not able to find my error here:

$(document).ready(function() {
$('#myForm input').on('change', function() {
   var intervall = $('input[name=selector]:checked', '#myForm').val();
    chrome.storage.sync.set({'intervall_selected': intervall}, function() {
  console.log('Value is set');
});
});
});

To be I don't see it. Maybe I'm getting old, so any help is really appreciated.

Thank you all