I have a problem with fullscreen ;My game run correctly on my computer. But when I tried to run it on my notebook it doesn't want to run in fullscreen. Here's the code

width = GetSystemMetrics(SM_CXSCREEN);
	height = GetSystemMetrics(SM_CYSCREEN);

	windowRect.left=(long)0;						
	windowRect.right=(long)width;					
	windowRect.top=(long)0;						
	windowRect.bottom=(long)height;					

	// definicja klasy okna
	windowClass.cbSize			= sizeof(WNDCLASSEX);
	windowClass.style			= CS_HREDRAW | CS_VREDRAW;
	windowClass.lpfnWndProc		= WndProc;
	windowClass.cbClsExtra		= 0;
	windowClass.cbWndExtra		= 0;
	windowClass.hInstance		= hInstance;
	windowClass.hIcon			= LoadIcon(NULL, IDI_APPLICATION);	
	windowClass.hCursor			= LoadCursor(NULL, IDC_ARROW);		
	windowClass.hbrBackground	= NULL;								
	windowClass.lpszMenuName	= NULL;								
	windowClass.lpszClassName	= "MojaKlasa";
	windowClass.hIconSm			= LoadIcon(NULL, IDI_WINLOGO);		

	if (!RegisterClassEx(&windowClass))
		return 0;

	if (fullScreen)							
	{
    DEVMODE screenSettings;
    memset(&screenSettings,0,sizeof(screenSettings));

    screenSettings.dmSize       = sizeof(DEVMODE);	
    screenSettings.dmPelsWidth  = width;			
    screenSettings.dmPelsHeight = height;			
    screenSettings.dmBitsPerPel = bits;				
    screenSettings.dmFields     = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT;

    
    if (ChangeDisplaySettings(&screenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL)
    {
      
      if (MessageBox(NULL, "Can't run in FULLSCREEN",
                           MB_YESNO | MB_ICONEXCLAMATION) == IDYES)
      {
        fullScreen = true;	
      }
      else
			{
				return FALSE;
			}
    }

So when I run it I recive this message : ""Can't run in FULLSCREEN"" Why? I'm not sure but I think it becouse this lines:

width = GetSystemMetrics(SM_CXSCREEN);
	height = GetSystemMetrics(SM_CYSCREEN);