sessionStorage not persisting between pages

My understanding is that sessionStorage values should persist after page reloads, but also between pages in the same site as long as the same tab is used.

In a particular page I can set 2 sessionStorage values. They persist on reload and when I come back to that page from another.

I need to pick up these values on another page in the same site but I cannot. Am I missing something in the documentation that states this is not possible or am I doing something wrong?

I have tried localStorage also but same problem.

Given a scenario where my 2 sessionStorage values are set, I test for them with the following if statement, but it never gets to it. I have also tried logging each to the console but no luck.

Thanks.

if (Modernizr.sessionstorage) {
var
a = document.getElementById('aId'),
b = document.getElementById('bId'),
c = document.getElementById('cId'),
d = document.getElementById('dId'),
e = document.getElementById('eId'),
f = parseInt(b.value)*parseInt(d.value)+4;

var startValues = function (){
a.value = b.value;
c.value = d.value;
e.value = f;
};

var sessValues = function (){
b.value = sessionStorage.getItem('thingOne');
d.value = sessionStorage.getItem('thingTwo');
startValues();
};


if(sessionStorage.getItem('thingOne') !== null || sessionStorage.getItem('thingTwo') !== null){
   sessValues();
}

else{
    sessionStorage.setItem('thingOne', 1);
    sessionStorage.setItem('thingTwo', 1);
    startValues();
}


b.addEventListener('input', function () {
sessionStorage.setItem('thingOne', b.value);
a.value = b.value;
}, false);

d.addEventListener('input', function () {
sessionStorage.setItem('thingTwo', d.value);
c.value = d.value;
}, false);

}