不支持bootstrap和paypal问题

I have create my theme for joomla 2.5 version and used virtue-mart for shopping cart. Every thing is working fine. User purchase from site with the help of paypal payment gateway and payment returns confirmed too. But when they enable the IPN notification URL then Paypal send a mail like

Please check your server that handles PayPal Instant Payment Notifications (IPN). IPNs sent to the following URL(s) are failing:

/index.php?option=com_virtuemart&view=pluginresponse&task=pluginnotification&tmpl=component

and when i click on this link then it will showing

500 - JHtml: :bootstrap not supported. File not found.

this error. I have just create my template for joomla 2.5.What the exactly issue. Please let me know

It seems you are trying to design a Template for Joomla 3, not for Joomla 2.5. For your information, the JHTML::bootstrap supported on Joomla 3 only, but you said you are creating template for Joomla 2.5. In case, you will need to remove JHTML::bootstrap from your code; if you want to use bootstrap, you will need to use it in another way.

Adding Bootstrap to Joomla:

<?php
$document = JFactory::getDocument();

// Adding bootstrap css
$document->addStyleSheet($url_to_css);

// Adding bootstrap javascript
$document->addScript($url_to_javascript);
?>