Segmentation fault (core dumped) error right after the assignment operator overload

Question

My programming assignment wanted me to make a class with a copy constructor and to overload the assignment operator (=). My code runs smoothly until I use the overloaded assignment operator, then it returns an error, segmentation fault (core dumped).

When I change it to use the copy constructor it doesn't return any errors, so I assume the problem is within the operator overloading part. Any idea what caused it? If it is the operator overloading part, what's the problem? Any help would be appreciated, thanks.

#define DefRow 2
#define DefCol 2
typedef double* DouArray;

class TwoD{
public:
    TwoD();
    TwoD(const TwoD& one);      //Copy Constructor
    ~TwoD();
    void setElement(int row, int column);
    double getElement(int row, int column);
    int getRows();
    int getCols();
    TwoD operator =(const TwoD& a);
private:
    double** Matrix;
    int MaxRows, MaxCols;
};

TwoD::TwoD(void){
    MaxRows = DefRow;
    MaxCols = DefCol;
    Matrix = new DouArray[MaxRows];
    for(int i = 0; i < MaxRows; i++){
        Matrix[i] = new double[MaxCols];
    }
}

TwoD::TwoD(const TwoD& one){
    MaxRows = one.MaxRows;
    MaxCols = one.MaxCols;
    Matrix = new DouArray[MaxRows];
    for(int i = 0; i < MaxRows; i++){
        Matrix[i] = new double[MaxCols];
    }
    for(int i = 0; i < MaxRows; i++){
        for(int j = 0; j < MaxCols; j++){
            Matrix[i][j] = one.Matrix[i][j];
        }
    }
}

TwoD::~TwoD(void){
    for(int i = 0; i < MaxRows; i++){
        delete [] Matrix[i];
    }
    delete [] Matrix;
    Matrix = NULL;
    MaxRows = 0;
    MaxCols = 0;
}

void TwoD::setElement(int row, int column){
    cin >> Matrix[row][column];
}

double TwoD::getElement(int row, int column){
    return Matrix[row][column];
}

int TwoD::getRows(){
    return MaxRows;
}

int TwoD::getCols(){
    return MaxCols;
}

operator overload here

TwoD TwoD::operator =(const TwoD& a){
    MaxRows = a.MaxRows;
    MaxCols = a.MaxCols;
    for(int i = 0; i < MaxRows; i++){
        for(int j = 0; j < MaxCols; j++){
            Matrix[i][j] = a.Matrix[i][j];
        }
    }
}

main here

int main(){
    int inrow, incol;
    cout << "Enter the row and column dimensions of the array." << endl;
    cin >> inrow >> incol;
    TwoD matrix2(inrow, incol);
    cout << "Enter " << inrow << " rows of " << incol << " doubles each." << endl;
    for(int i = 0; i < inrow; i++){
        for(int j = 0; j < incol; j++){
            matrix2.setElement(i, j);
        }
    }
    TwoD temp2 = matrix2;
    cout << "Echoing the 2 dim. array, matrix2" << endl;
    for(int i = 0; i < temp2.getRows(); i++){
        for(int j = 0; j < temp2.getCols(); j++){
            cout << temp2.getElement(i, j) << " ";
        }
        cout << endl;
    }
    cout << "Assigning matrix2 to matrix3" << endl;
    TwoD matrix3;

    matrix3 = matrix2; //I got the error here

    cout << "Displaying the 2 dim. array, matrix3 resulting from assignment" << endl;
    cout << "Rows " << matrix3.getRows() << " Cols " << matrix3.getCols() << endl;
    for(int i = 0; i < matrix3.getRows(); i++){
        for(int j = 0; j < matrix3.getCols(); j++){
            cout << matrix3.getElement(i, j) << " ";
        }
        cout << endl;
    }
    return 0;
}

Expected result:

Enter the row and column dimensions of the array
3 4
Enter 3 rows of 4 doubles each.
1.0 1.0 1.0 1.0
2.0 2.0 2.0 2.0
3.0 3.0 3.0 3.0
Echoing the 2 dim. array, matrix2
1 1 1 1
2 2 2 2
3 3 3 3
Assigning matrix2 to matrix3
Displaying the 2 dim. array, matrix3 resulting from assignment
Rows 3 Cols 4
1 1 1 1
2 2 2 2
3 3 3 3

Actual result:

Enter the row and column dimensions of the array.
3 4
Enter 3 rows of 4 doubles each.
1.0 1.0 1.0 1.0
2.0 2.0 2.0 2.0
3.0 3.0 3.0 3.0
Echoing the 2 dim. array, matrix2
1 1 1 1
2 2 2 2
3 3 3 3
Assigning matrix2 to matrix3
Segmentation fault (core dumped)