从自定义目录属性中获取空

I add some attributes to category and it shows at adminhtml catalog page,but I can get nothing from frontend page,it is work on my computer,but after I move it to the hostgator it get empty,please help.

$this->startSetup();
$this->addAttribute('catalog_category', 'selectcol', array(
    'group' => 'Navigation',
    'type' => 'varchar',
    'input' => 'select',
    'source' => 'mact/category_attribute_source_selectcol',
    'label' => 'Select no of column',
    'backend' => '',
    'default'  => '4',
    'visible' => true,
    'required' => false,
    'visible_on_front' => true,
    'wysiwyg_enabled' => true,
    'is_html_allowed_on_front'  => true,
    'global' => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,
    'position' => 150,
));

 $this->endSetup();

And get the attribute from block php file.

  $cat = Mage::getModel('catalog/category')->load(43);
  $cat->getSelectcol();//get nothing.

Thank you so much