Vector iterator not dereferencable with std::shared_ptr<>

I am having trouble dereferencing a found shared_ptr from a vector after std::find. Could someone explain why this is the case?

    extern std::vector< shared_ptr<King::Actor> > selected
    foo(const std::vector<std::shared_ptr<Actor>> &playerUnits)
    {
        std::vector<std::shared_ptr<Actor>>::const_iterator result;
        result = std::find(std::begin(playerUnits), std::end(playerUnits), selected.back());

        if (result != std::end(playerUnits))
            return *std::next(result); // found
        return nullptr;
    }
enter code here

closest answer is https://stackoverflow.com/questions/301959/vector-iterator-not-dereferencable#= I believe it both found it and not the end of the vector, yet it still reports not dereferencable.