Error code 2556,2040

I keep getting error code error C2556: 'int myArray::operator const' : overloaded function differs only by return type from 'int &myArray::operator const'

see declaration of 'myArray::operator []'

error C2040: 'myArray::operator []' : 'int (int) const' differs in levels of indirection from 'int &(int) const'

This is my myArray .cpp file

#include <iostream>
#include "myArray.h"

using namespace std;

    myArray::myArray(int newSize)
    {
        startIndex=0;
        size = newSize;
        PtrArray = new int[size];
        for(int i=0; i< size; i++)
            PtrArray[i] = 0;
    }

    myArray::myArray(int newStartIndex, int newSize)
    {
        startIndex = -newStartIndex;
        size = newSize;
        PtrArray= new int [size + startIndex];

        for(int i=0; i< (size + startIndex); i++)
            PtrArray[i]= 0;
    }

    myArray::~myArray()
    {
        delete [] PtrArray;
    }

    int &myArray::operator[] (int index)
    {
        if ((index <-startIndex || index >= size))
        {
            cerr<<"Error: Index "<<index<<" is our of range"<<endl;
            system("pause");
            exit(1);
        }

        return PtrArray[index+startIndex];
    }

            int myArray:: operator[](int index) const
            {
                if (index <-startIndex || index >= size)
                {
                    cerr<<"Error:Index"<< index<<"isout of range"<<endl;
                        system("pause");
                        exit(2);
                }

        return PtrArray[index + startIndex];
            }

This is my program .cpp code

#include <iostream>
#include "myArray.h"

using namespace std;

int main()
{
    myArray list(5);
    myArray myList(2,13);
    myArray yourList(-5,9);

for(int i=0; i<5; i++)
    list[i]=i*i;

for(int j=2; j<13; j++)
    myList[j]=j*j;

for(int k=-5; k<9; k++)
    yourList[k]=k*k;

cout<<"The elements stored in the first object list are:"<<endl;

for(int i=0; i<5; i++)
{
    cout<<"list["<<i<<"[\t\t="<<list[i]<<endl;
}

cout<<"The elements stored in the second object myList are:"<<endl;

for(int j=2; j<13; j++)
{
    cout<<"myList["<<j<<"]\t="<<myList[j]<<endl;

}

cout<<"The elements stored in the third object yourList are:"<<endl;

for (int k=-5;k<9;k++)
{
    cout<<"yourList["<<k<<"]\t"<<yourList[k]<<endl;
}

cin>>yourList[-13];
system("pause");
return 0;
}

This is my myArray header:

#ifndef H_myArray
#define H_Array
#include <iostream>

using namespace std;

class myArray
{
public:
    myArray(int);
    myArray(int,int const);
    ~myArray();

    int &operator[](int);
    int &operator[](int) const;

private:
    int startIndex;
    int size;
    int *PtrArray;


};

#endif

via Chebli Mohamed