C++ :: Bool Logic For Date Validation

My issue is regardless of which date I input its always defaulting to the values I have set in my constructor in my implementation file in the else statement. So the values always default to 3/15/2006 I think its something to do with the logic in my bool function but I may be incorrect.

header
//date.h header
#include <iostream>
#include <string>
using namespace std;

enum DateFormat {numeric, standard, alternative};
const int MIN_YEAR = 1900;
const int MAX_YEAR = 2015;

[Code] ....