ajax button doesnt fire callback function
try adding '#submit':

$operations['delete'] = array(
  '#type' =&gt; 'submit',
  '#value' =&gt; t('Delete'),
  '#ajax' =&gt; array(
    'wrapper' =&gt; 'wizard-form-wrapper',
    'callback' =&gt; 'application_wizard_callback'
  ),
  '#submit' =&gt; array('application_wizard_submit'),
);