Adding states to the game created in the SFML Book

[Clockwork]

Hello everybody!

So I followed the SFML book and now I'm just editing it for a personal project, but I've encountered a project.  I'm trying to add a new state that can be accessed by a button the menu.  The code for the state compiles just fine, the button shows up and everything.  But whenever I try to click on the button I get this message (in the attached pics).  The code at Statestack,cpp, line 69 is this:

 

Could somebody please let me know whats going wrong?
Thanks! 

[Nexus]

Corrected code tags:

The code at Statestack,cpp, line 69 is this:

State::Ptr StateStack::createState(States::ID stateID)
{
        auto found = mFactories.find(stateID);
        assert(found != mFactories.end()); /* This line in particular */

        return found->second();
}

You have to register the states in the stack, so it knows how to create a new instance for a specific enumerator. Here you see how it works.

[Clockwork]

* sigh *

I figured it would be something that simple.  Well, thanks Nexus, it works perfectly now!