Cannot write stl's map into a file

[dpreznik]

Maybe somebody could please help me understand why I fail to write stl's map of vectors into a file using CFile::Write()?

typedef std::vector<CLocation> LocationArray;
typedef std::map<int, LocationArray > MapLocationArray;

...

int iSize = sizeof(m_mapLocations);
		cf->Write(&iSize, sizeof(iSize));
		cf->Write(&m_mapLocations, iSize);

When I am writing, the m_mapLocations contains valid data. But when I read from file, it is empty, though the iSize is correct...

int iSize = 0;
		cf->Read(&iSize, sizeof(iSize));
		if(iSize > 0)
			cf->Read(&m_mapLocations, iSize);