Drupal 7 Forms API - AJAX Forms error: An illegal choice has been detected. Please contact the site administrator - drupal-7

Question

I have a form set up where a users selects an item from a drop down. Once that item is selected another drop down is populated. Then depending on the value that is selected from the second drop down a fieldset may or may not be shown. If the field set is shown there is a field and a button. By clicking the button you add another copy of the same field. Once there is more than one a remove one button shows up as well. I got the basis for the code from here:
http://api.drupal.org/api/examples/ajax_example%21ajax_example_graceful_degradation.inc/function/ajax_example_add_more/7
The problem is when I click 'Add Another Survey Question' the first time it works fine and add a field. When I click it a second time or when I click remove now that there are two, I get this error: 'An illegal choice has been detected. Please contact the site administrator.'
What am I doing wrong?
Here's my code:
function touchpoints_addmetric_form($form, &$form_state, $tp_id) {
$selectedType = isset($form_state['values']['type']) ? $form_state['values']['type'] : FALSE;
$types = db_query('SELECT * FROM {touchpoints_metric_types}') -> fetchAllKeyed(0, 1);
$form['#tree'] = TRUE;
$form['type'] = array(
'#type' => 'select',
'#title' => t('Metric Type'),
'#options' => $types,
'#required'=>TRUE,
'#ajax' => array(
'event' => 'change',
'wrapper' => 'method-wrapper',
'callback' => 'touchpoints_method_callback'
)
);
$form['measurementmethod'] = array(
'#type' => 'select',
'#title' => t('Measurement Method'),
'#required'=>TRUE,
'#prefix' => '<div id="method-wrapper">',
'#suffix' => '</div>',
'#options' => _get_methods($selectedType)
);
$form['survey'] = array('
#type' => 'fieldset',
'#collapsible' => FALSE,
'#states' => array(
'visible' => array(
array(
array(':input[name="measurementmethod"]' => array('value' => '5')),
'xor',
array(':input[name="measurementmethod"]' => array('value' => '6')),
'xor',
array(':input[name="measurementmethod"]' => array('value' => '7'))
)
)
)
);
$form['survey']['contents'] = array(
'#type' => 'fieldset',
'#collapsible' => FALSE,
'#prefix' => '<div id="survey-div">',
'#suffix' => '</div>',
);
if (empty($form_state['num_surveys'])) {
$form_state['num_surveys'] = 1;
}
for ($i = 1; $i <= $form_state['num_surveys']; $i++) {
$form['survey']['contents']['survey_question'][$i] = array(
'#type' => 'textfield',
'#title' => t('Survey Question ' . $i),
'#size' => 70, '#maxlength' => 100,
);
}
$form['survey']['contents']['addsurvey'] = array(
'#type' => 'submit',
'#value' => t('Add Another Survey Question'),
'#submit' => array('touchpoints_metrics_survey_add_one'),
'#limit_validation_errors' => array(),
'#ajax' => array(
'callback' => 'touchpoints_metrics_survey_callback',
'wrapper' => 'survey-div',
),
);
if ($form_state['num_surveys'] > 1) {
$form['survey']['contents']['removesurvey'] = array(
'#type' => 'submit',
'#value' => t('Remove A Survey Question'),
'#submit' => array('touchpoints_metrics_survey_remove_one'),
'#limit_validation_errors' => array(),
'#ajax' => array(
'callback' => 'touchpoints_metrics_survey_callback',
'wrapper' => 'survey-div',
),
);
}
return $form;
}
function _get_methods($selected) {
if ($selected) {
$methods = db_query("SELECT * FROM {touchpoints_m_methods} WHERE mt_id=$selected") -> fetchAllKeyed(0, 2);
} else {
$methods = array();
}
return $methods;
}
function touchpoints_method_callback($form, &$form_state) {
return $form['measurementmethod'];
}
function touchpoints_metrics_survey_add_one($form, &$form_state) {
$form_state['num_surveys']++;
$form_state['rebuild'] = TRUE;
}
function touchpoints_metrics_survey_remove_one($form, &$form_state) {
if ($form_state['num_surveys'] > 1) {
$form_state['num_surveys']--;
}
$form_state['rebuild'] = TRUE;
}
function touchpoints_metrics_survey_callback($form, &$form_state) {
return $form['survey']['contents'];
}

Answer 1

I have encountered this error a few times, and this is what I found:
This is Drupal's way of saying "Hey, you tried to submit this form with a , checkbox or radio button option that wasn't included in the original form definition! That's not allowed." - See more at: http://proofgroup.com/blog/2008/jul/debugging_mysterious_illegal_choice_has_been_detected_please_contact_site_administrato#sthash.vDNmqslL.dpuf
Instead of custom code, maybe you should consider module Conditional Fields
Or a work around: '#validate' => TRUE source

Answer 2

Actually, it's '#validated' => TRUE.