This statement tries to invoke class::member(), either directly or as object.member(). However, no such member function is available from that class. Check the spelling of the member name and the class or object name. If the reference is class::member(), review the declaration of the class for the correct spelling of the names of its members. If the reference is through an object, make sure the object is declared as having the class you intended. You can only call members of the stated class (the class it is declared to have) of an object. If you want to call a member of an actual class (the class that you think will be present at execution time), use the CAST operator.