arrays of different types

[DNA7433]

ok, im just starting to understand polymorphism, its a cool subject but im getting a few errors and im totally lost now

#include<iostream>
#include<vector>

using namespace std;

/////////////////////////////////////////////////////

class MenuBase{};

/////////////////////////////////////////////////////

template<class InputType, class ReturnType, class ParamType1, class ParamType2>
class MenuItem : public MenuBase
{
public:
	InputType GetInput(void){return m_Input;}
	void SetInput(InputType Input){m_Input = Input;}

private:
	InputType m_Input;
};

/////////////////////////////////////////////////////

class Menu
{
public:
	Menu(vector<MenuBase*> items)
		:m_items(items)
	{}

	int GetSize(void){return m_items.size();}

private:
	vector<MenuBase*> m_items;
};

/////////////////////////////////////////////////////

int main()
{
	vector<MenuBase*> menu(3);
	
	MenuItem<int, int, char, int> menuitem1;
	menuitem1.SetInput(100);
	menu[0] = menuitem1;
	
	MenuItem<char, int, int, long> menuitem2;
	menuitem2.SetInput('A');
	menu[1] = menuitem2;
	
	MenuItem<bool, bool, int, char> menuitem3;
	menuitem3.SetInput(true);
	menu[2] = menuitem3;

	Menu theMenu(menu);

	cout << theMenu.GetSize() << endl;

	return 0;
}

i get these 3 errors
C:\Dan's Stuff\School\C++ Projects\CS4\Polymorphism\TempMenu.cpp(46) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'class MenuItem<int,int,char,int>' (or there is no acceptable conversion)
C:\Dan's Stuff\School\C++ Projects\CS4\Polymorphism\TempMenu.cpp(50) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'class MenuItem<char,int,int,long>' (or there is no acceptable conversion)
C:\Dan's Stuff\School\C++ Projects\CS4\Polymorphism\TempMenu.cpp(54) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'class MenuItem<bool,bool,int,char>' (or there is no acceptable conversion)