C++ template specialization - run for any pointer to a subclass to a type [duplicate]

This question already has an answer here:

• Template function that matches only certain types? 3 answers

I have a templated function which I want to have two paths that it can follow: (very simplified for obvious reasons)

// Implementation A
template <class T>
T getValue( uint8_t id )
{
    return dynamic_cast<T>( createClass( id ) );
}

// Implementation B
template <class T>
T getValue( uint8_t id )
{
    return id + 1;
}

In this usage of example above, I have a class MyClass, and then a class MySubClass : public MyClass

I then want to be able to call any of the following:

getValue<MyClass*>( 3 ) // calls Implementation A
getValue<MySubClass*>( 4 ) // calls Implementation A
getValue<int>( 5 ) // calls Implementation B
getValue<float>( 6 ) // calls Implementation B

Now I know that I can directly specialize the template with MyClass*, but that wouldn't help for MySubClass*

I've done some googling for this, but haven't found an answer that seems to quite give me the push I'm looking for.

I've got as far as:

template <typename T>
typename std::enable_if<std::is_base_of<NvPacket*, T>::value, T>::type
getValue( uint8_t id )
{
    return dynamic_cast<T>( createClass( id ) );
}

template <typename T>
typename std::enable_if<!std::is_base_of<NvPacket*, T>::value, T>::type
getValue( uint8_t id )
{
    return id + 1;
}

But when I go to compile this with the following being called:

getValue<uint8_t>();

I get a compiler error of:

ambiguous call to overloaded function