javascript to change innerHTML
===

I want to change content of div "act" using nextSibling of another div.  
But result is - undefined.

    function inner(){
    var abc = document.getElementById("start").nextSibling;
    document.getElementById("act").innerHTML = abc.innerHTML;
     }

    <img id="btnRight" src="img/btnRight.png" onclick="inner()">
    <div id="act"><img src="img/home01.jpg"></div>

    <div id="store">
    <div id="start">
    <img src="img/img01.jpg">
    </div>

    <div>
    <img src="img/img02.jpg"> //wanted to place into "act"
    </div>

    <div id="end">
    <img src="img/img03.jpg">
    </div>
    </div>

