On a mage site using sagepay, inside the Sagepaysuite model there is a call to a class
$xml = new Ebizmarts_Simplexml_Element('<customer />');
The class 'Ebizmarts_Simplexml_Element' can be found in - root/lib/Ebizmarts/Simplexml/Element.php
class Ebizmarts_Simplexml_Element extends Varien_Simplexml_Element
I can see from checking apache logs that this cannot be found
Class 'Ebizmarts_Simplexml_Element' not found in <path to payment.php
I assume an include of this file before the class is called would work but this cannot be best practice and may not be enough if the class is required in other areas of the extension that I have not yet noticed. How exactly are lib files loaded in Magento and any ideas why it is not getting it in this case.