function rotateBanner(div_id,nextIdNum, milisec) {
    var picArray = document.getElementById(div_id).getElementsByTagName("div");

    for (var i=0;i<picArray.length;i++) {
        if (i == nextIdNum) {picArray[i].style.display = "block";}
        else                {picArray[i].style.display = "none";}
    }

    if (nextIdNum == (picArray.length-1)) {nextIdNum = 0;}
    else                                  {nextIdNum +=1;}

    setTimeout(function(){rotateBanner(div_id,nextIdNum, milisec);}, milisec);
}