Magento – Source model “customer/source_option” not found for attribute “customeractivate”

Hi I'm creating column/field for Customer Activate which is option column/field. it's created from eva_attribute and showing customer admin grid also when I click on edit particular customer record it's returning an error.

Error is:
Source model "customer/source_option" not found for attribute "customeractivate"

my code is:

C:\xampp\htdocs\magento\app\code\local\Easylife\Customattribute\sql\customattribute_setup\upgrade-0.1.1-0.1.2.php

<?php
$installer = $this;
$installer->startSetup();
$setup = new Mage_Eav_Model_Entity_Setup('core_setup');
$entityTypeId     = $setup->getEntityTypeId('customer');
$attributeSetId   = $setup->getDefaultAttributeSetId($entityTypeId);
$attributeGroupId = $setup->getDefaultAttributeGroupId($entityTypeId, $attributeSetId);
$setup->addAttribute('customer', 'customeractivate', array(
    'label'             => 'Customer Activate',
    'type'              => 'int',
    'input'             => 'select',
    'backend'           => 'eav/entity_attribute_backend_array',
    'frontend'          => '',
    'source'            => 'customer/group_collection',
    'global'            => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL,
    'visible'           => true,
    'required'          => true,
    'user_defined'      => true,
    'searchable'        => false,
    'filterable'        => false,
    'comparable'        => false,
    'option'            => array ('value' => array('optionone' => array('Yes'),
                                                   'optiontwo' => array('No'),)),
    'visible_on_front'  => false,
    'visible_in_advanced_search' => false,
    'unique'            => false
));
$setup   = Mage::getSingleton("eav/config")->getAttribute("customer", "customeractivate");
$used_in_forms=array();

$used_in_forms[]="adminhtml_customer";
$setup->setData("used_in_forms", $used_in_forms)
    ->setData("is_used_for_customer_segment", true)
    ->setData("is_system", 0)
    ->setData("is_user_defined", 1)
    ->setData("is_visible", 1)
    ->setData("sort_order", 100)
;
$setup->save();
$installer->endSetup();

C:\xampp\htdocs\magento\app\code\core\Mage\Adminhtml\Block\Customer\Grid.php

<?php
class Mage_Adminhtml_Block_Customer_Grid extends Mage_Adminhtml_Block_Widget_Grid
{
...
 protected function _prepareColumns()
    {
 $this->addColumn('customeractivate',
            array(
                'header'=> Mage::helper('customer')->__('Customer Active'),
                'width' => '70px',
                'index' => 'status',
                'type'  => 'options',
                'options' => Mage::getResourceModel('customer/group_collection')->getOptionArray(),
            ));
     }
..
}

C:\xampp\htdocs\magento\app\code\core\Mage\Customer\Model\Resource\Group\Collection.php

<?php

class Mage_Customer_Model_Resource_Group_Collection extends Mage_Core_Model_Resource_Db_Collection_Abstract
{

    const STATUS_ENABLED    = 1;
    const STATUS_DISABLED   = 2;

...
  static public function getOptionArray()
    {
        return array(
            self::STATUS_ENABLED    => Mage::helper('customer')->__('Yes'),
            self::STATUS_DISABLED   => Mage::helper('customer')->__('No')
        );
    }
...
}

Can you please tell me where I went wrong?

thanks in advance.