template parameter to dynamic_pointer_cast

What's wrong with this code?

class Event;

class EventPtr : public std::shared_ptr<Event>
{
public:
    template<typename T>
    std::shared_ptr<T> castTo() {
        return std::dynamic_pointer_cast<T>(this);
    }
};

I get the following compile error: no matching function for call to 'dynamic_pointer_cast'

Below is the usage:

void SomeClass::onEvent(EventPtr event)
{
    auto e = event.castTo<SomeEvent>();
    // using casted event
}