Class inheritance issue with XmlNodeList

XmlNodeList is an Abstract class and is meant to be a base class. You cannot instantiate an Abstract class you can only inherit from it. An Abstract class is a model of what the derived class should have in the way of data and operations. Abstract classes provide methods without any implementation. It is up to the derived class to provide the implementation for those methods. If you don't provide any implementation for an abstract method then you get the complier error that you mentioned. You must provide some form of implementation for the methods you mentioned, even if it is just a semi-colon. So to get by your problem just add the method signatures, add braces and put a semi-colon inside those brace. Or some other code that you might want there. Hope this helps.