Abstract klasse, polymorfi

Hvad er forkert her?? jeg kan ikke lave en
objects=new CWall('*');
fejlmeldning er
'type cast' : conversion from 'CWall *' to 'ICBoardObjects *' exists, but is inaccessible   

ICBoardObjects er en abstract klasse med en pure virtual funktion.


------------------------------------------------------------------
class ICBoardObjects{

public:
    char obstracle;
    virtual char getObstracle()=0;
};
------------------------------------------------------------------

#include "CWall.h"

class CGameBoard{
private:
    ICBoardObjects* objects;
    int x;
    int y;
public:
    CGameBoard();
    void makeMatrix();
};

CGameBoard::CGameBoard(){
    objects=new CWall('*');
}