Form ajax add more button added via another ajax callback not working
@NabajitRoy my idea is 


Never use drupal_render() manual calls (return $form array as-is)
Move all the form generation code into form constructor( create_report_form() ), AJAX
callback should not create new elements for form but only
create_report_form() should
AJAX callbacks should only return element form (not generate them)
e.g. return $form['attributes']['submit'] and may be
$form_state['rebuild'] = true; if needed.
To know in create_report_form() if it was called by AJAX request
button check the $form_state['triggering_element'] in it.
I feel that using '#type' =&gt; 'submit' instead of '#type' =&gt; 'button'
is better


 https://www.drupal.org/node/752056