js div invisible

function toggleShowDiv(pass) {

        var divs = document.getElementsByTagName('div');
        for(i=0;i<divs.length;i++) {
                if (divs[i].id.match(pass)) {
                        if (document.getElementById) {                                                  // compatible with IE5 and NS6
                                if (divs[i].style.visibility=="visible")
                                        divs[i].style.visibility="hidden";
                                else
                                        divs[i].style.visibility="visible";
                        } else if (document.layers) {                                                   // compatible with Netscape 4
                                if (document.layers[divs[i]].display=='visible')
                                        document.layers[divs[i]].display = 'hidden';
                                else
                                        document.layers[divs[i]].display = 'visible';
                        } else {
                                if (document.all.hideShow.divs[i].visibility=='visible')                // compatible with IE4
                                        document.all.hideShow.divs[i].visibility = 'hidden';
                                else
                                        document.all.hideShow.divs[i].visibility = 'visible';
                        }
                }
        }
}



<input type="checkbox" onclick="javascript:toggleShowDiv('256')">


<div id="256a" style="visibility:hidden" >
                                                <input value="<?php echo $maxallsession ?>" name="maxallsession" />
<a href="javascript:maxallsession(86400)">1day(s)</a>
<a href="javascript:maxallsession(259200)">3day(s)</a>
<a href="javascript:maxallsession(604800)">1week(s)</a>
<a href="javascript:maxallsession(1209600)">2week(s)</a>
<a href="javascript:maxallsession(1814400)">3week(s)</a>
<a href="javascript:maxallsession(2592000)">1month(s)</a>
<a href="javascript:maxallsession(5184000)">2month(s)</a>
<a href="javascript:maxallsession(7776000)">3month(s)</a>
                                                <br/>
                                                </font>
</div>