CLI copy constructors for noob

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C++/CLI

I'm a "returning" student and a noob to this forum. Having big trouble with chap on CLI classes (Horton C++ 2010 chap 8).

My practice project currently contains Address objects that have city name, street name, street number, and zip.

All works well until I try to implement a copy constructor. The book says to create a copy constructor for CLI must pass argument as "const tracking reference" (it actually says 'const reference' but the example uses %).
This is my "Address" class:

// Address.h - Contains ADDRESS class
#ifndef ADDRESS_H
#define ADDRESS_H

ref class Address : public City
{
private:
	System::String^ street;
	System::Int32	address;
	System::Int32	zip;

public:
	// CONSTRUCTOR, No-arg
	Address()
	{
		stateID = StateCODE::missing;
		cityName = "missing";
		street = "missing";
		address = 0;
		zip = 0;
	}
	// CONSTRUCTOR
	Address(StateCODE sc, System::String^ cn, System::String^ st)
	{
		stateID = sc;
		cityName = cn;
		street = st;
	}
	// Copy CONSTRUCTOR ("const tracking reference" parameter p. 415)
	//Address( Address% a)
	Address(const Address% a)
	{
		stateID = a.stateID;
		//cityName = a.cityName;
		street = a.street;
		address = a.address;
		zip = a.zip;
	}		
};

#endif

This is my "State" class:

// State.h - Contains STATE class
#ifndef STATE_H
#define STATE_H

// StateCODE are alphabetized according to their full name, not abbreviations.
public enum class StateCODE
{
	missing,
	AL, AK, AZ, AR, CA, CO, CT, DE, DC, FL, GA, HI, ID, IL, IN, IA, KS,
	KY, LA, ME, MD, MA, MI, MN, MS, MO, MT, NE, NV, NH, NJ, NM, NY, NC,
	ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY
};


ref class State
{
private:
	StateCODE sCODE;

public:
	// Default constructor
	State()	{	}

	// Function to return name of state as a String^.
	System::String^ name()
	{
		switch (safe_cast<int>(this->sCODE))								// sCODE is an enum.
		{
		case 0: return "missing";		break;
		case 1: return "Alabama";		break;
		case 2: return "Alaska";		break;
		case 3: return "Arizona";		break;
		case 4: return "Arkansas";		break;
		case 5: return "California";		break;
		case 6: return "Colorado";		break;
		case 7: return "Connecticut";		break;
		case 8: return "Delaware";		break;
		case 9: return "District of Columbia";	break;
		case 10: return "Florida";		break;
		case 11: return "Georgia";		break;
		case 12: return "Hawaii";		break;
		case 13: return "Idaho";		break;
		case 14: return "Illinois";		break;
		case 15: return "Indiana";		break;
		case 16: return "Iowa";			break;
		case 17: return "Kansas";		break;
		case 18: return "Kentucky";		break;
		case 19: return "Louisiana";		break;
		case 20: return "Maine";		break;
		case 21: return "Maryland";		break;
		case 22: return "Massachusetts";	break;
		case 23: return "Michigan";		break;
		case 24: return "Minnesota";		break;
		case 25: return "Mississippi";		break;
		case 26: return "Missouri";		break;
		case 27: return "Montana";		break;
		case 28: return "Nebraska";		break;
		case 29: return "Nevada";		break;
		case 30: return "New Hampshire";	break;
		case 31: return "New Jersey";		break;
		case 32: return "New Mexico";		break;
		case 33: return "New York";		break;
		case 34: return "North Carolina";	break;
		case 35: return "North Dakota";		break;
		case 36: return "Ohio";			break;
		case 37: return "Oklahoma";		break;
		case 38: return "Oregon";		break;
		case 39: return "Pennsylvania";		break;
		case 40: return "Rhode Island";		break;
		case 41: return "South Carolina";	break;
		case 42: return "South Dakota";		break;
		case 43: return "Tennessee";		break;
		case 44: return "Texas";		break;
		case 45: return "Utah";			break;
		case 46: return "Vermont";		break;
		case 47: return "Virginia";		break;
		case 48: return "Washington";		break;
		case 49: return "West Virginia";	break;
		case 50: return "Wisconsin";		break;
		case 51: return "Wyoming";		break;

		default: return "";
		}
	}

	property StateCODE stateID
	{
		StateCODE get(){ return sCODE; }
		void set(StateCODE value){ sCODE = value; }
	}
};

#endif

The stateID = a.stateID; line of the 'Address' class COPY CONSTRUCTOR causes the trouble, as does the "cityName = a.cityName" which I've commented out. When I compile this I get:

error C2662: 'StateCODE State::stateID::get(void)' : cannot convert 'this' pointer from 'const Address' to 'State %' Conversion loses qualifiers

If I remove "const" qualifier from copy constructor it works. If I try to make 'State' property and it's get accessor const it complains about the set accessor. If I also make the set accessor const, then the copy constructor doesn't work.

What's going on and what can I do?

Thanks in advance for your help