How do I call a parameterless function pointer from within a class?

This is an extended new question from my last post: How do I use function pointers within this class?

I have three members in my class:

        void (X2D::Graphics::OpenGL::Circle::*draw_ptr)(void);
        void draw_filled();
        void draw_outlined();

This method shows how they are assigned:

void Circle::fill(const bool fill)
{
    m_fill = fill;

    if (fill)
        draw_ptr = &Circle::draw_filled;
    else
        draw_ptr = &Circle::draw_outlined;
} 

Thus, the 'draw_ptr' function pointer points to either draw_filled() or draw_outlined().

Within the same class, I have the following method:

void draw() { this->draw_ptr; }

However, I placed a debugging point within draw_filled(), which is where it should be calling, and calling draw() does not go in draw_filled(). Because draw_ptr is parameterless, I'm almost positive it's doing nothing but returning the address to the function. However, I want to call what's in this address.

Using draw_ptr() does not work, because I get the error: error C2064: term does not evaluate to a function taking 0 arguments

Am I calling draw_ptr wrong?