Drupal Fields Ajax not working I have added fields to my entity via Field UI and trying to fire an ajax callback but it is not working.

This works

$form['customField'] = array(
        '#type' =&gt; 'textfield',
);

$form['customField']['#ajax'] = array(
      'callback' =&gt; 'just_test',
      'wrapper' =&gt; 'membership_suggestions',
);


But this does not ('field_member_first_name' is added to the entity via Field UI and is a text field)

$form['field_member_first_name']['#ajax'] = array(
    'event' =&gt; 'blur',
    'callback' =&gt; 'just_test',
    'wrapper' =&gt; 'membership_suggestions',
);


Thanks a lot.
Since the fields were attached via Field API, I have to do this way

$form['field_member_last_name'][LANGUAGE_NONE][0]['value']['#ajax'] = array(
    'event' =&gt; 'blur',
    'callback' =&gt; 'get_suggestion_by_name',
    'wrapper' =&gt; 'suggestions_by_name',
    'method' =&gt; 'html',
);