Where can I find MapPoint Control decument for VC?

I could find reference in MSDN:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/mappoint2004/bizaboutprogramming.asp

But the example and description are all in VB.

I tried a VB sample, and it works. But I want to write an application with VC6.0. I created a dialog application, and put the following code in

BOOL CT02Dlg::OnInitDialog()
{
...
// TODO: Add extra initialization here
VARIANT geoMapNorthAmerica;
VariantInit( &geoMapNorthAmerica );
V_VT(&geoMapNorthAmerica) = VT_I4;
V_I4(&geoMapNorthAmerica) = 1;

m_map_point.NewMap(geoMapNorthAmerica);

return TRUE; // return TRUE unless you set the focus to a control
}

in which m_map_point is the CMappointCtrl data member associated
with the MapPoint Control.

The code could pass the building, but has running error of
"Debug Assertion Failed".

Thanks for any advices.