sercai on "[Plugin: WooCommerce - APG SMS Notifications] Fatal error: Class 'Services_Twilio_Resource' not found"

Hello,

I have Woocommerce 2.1.2 and I am trying to send an SMS with your pluging and Twilio.
But everytime I try to submit an order, I get the following Warning and Error:

Warning: include() [function.include]: Failed opening '[...]/wp-content/plugins/woocommerce-apg-sms-notifications/lib/Twilio/Resource.php' for inclusion (include_path='.:/usr/local/php-5.3.27/share/pear') in [...]/wp-content/plugins/woocommerce-apg-sms-notifications/lib/twilio.php on line 15

Fatal error: Class 'Services_Twilio_Resource' not found in [.]]]/wp-content/plugins/woocommerce-apg-sms-notifications/lib/twilio.php on line 43

Is it someting related to PHP-5.3.27 ?

Thanks,

https://wordpress.org/plugins/woocommerce-apg-sms-notifications/