I'm learning to use the GUI Class to make graphics in my programs. I have create an extremely simple program to see if GUI works, but it doesn't -_-;; here is the code:

Code:
/*
    Olympic Symbol Program
*/

#include <lvp\gui_top.h>

class GuiClass
{
      public:
      GuiClass();
      void GuiMouseClick(int x, int y);
      void GuiPaint();
      String Title();
      private:
};

GuiClass::GuiClass()
{
}

String GuiClass::Title()
{
       return ("The Olympic Symbol!");
}

void GuiClass::GuiMouseClick (int x, int y)
{
}

void GuiClass::GuiPaint()
{
     Circle(180,200,50);
     Circle(250,200,50);
     Circle(320,200,50);
     Circle(215,270,50);
     Circle(285,270,50);
}

#include <lvp\gui_bot.h>
yes, very simple, but when I compile, I get this error:
C:\DEV-C_~1\INCLUDE\lvp\gui_bot.h: In function `int WinMain(HINSTANCE__ *, HINSTANCE__ *, CHAR *, int)':
and this (2 times):
474 c:\dev-c_~1\include\lvp\gui_bot.h
warning: converting NULL to non-pointer type

Can anyone help me fix this? o.O