'identifier' : too many access modifiers on the base class
The specified base class had more than one access modifier.
A base class or structure can be declared with only one access modifier (public, private, or protected).
The following is an example of this error:
class A { };
class B { };
class C : private public A { }; // error
class D : private A { }; // OK
class E : public A, private B { }; // OK