following script gives error when i validate on w3c

<script type="text/javascript">
ddaccordion.init({
    headerclass: "submenuheader", //Shared CSS class name of headers group
    contentclass: "submenu", //Shared CSS class name of contents group
    revealtype: "click", //Reveal content when user clicks or onmouseover the header? Valid value: "click", "clickgo", or "mouseover"
    mouseoverdelay: 200, //if revealtype="mouseover", set delay in milliseconds before header expands onMouseover
    collapseprev: true, //Collapse previous content (so only one open at any time)? true/false
    defaultexpanded: [], //index of content(s) open by default [index1, index2, etc] [] denotes no content
    onemustopen: false, //Specify whether at least one header should be open always (so never all headers closed)
    animatedefault: false, //Should contents open by default be animated into view?
    persiststate: true, //persist state of opened contents within browser session?
    toggleclass: ["", "active"], //Two CSS classes to be applied to the header when it's collapsed and expanded, respectively ["class1", "class2"]
    togglehtml: ["suffix", "<img src="images/plus.gif" class="statusicon" alt=" " />", "<img src="images/minus.gif" class="statusicon" alt=" " />"], //Additional HTML added to the header when it's collapsed and expanded, respectively  ["position", "html1", "html2"] (see docs)
    animatespeed: "fast", //speed of animation: integer in milliseconds (ie: 200), or keywords "fast", "normal", or "slow"
    oninit:function(headers, expandedindices){ //custom code to run when headers have initalized
        //do nothing
    },
    onopenclose:function(header, index, state, isuseractivated){ //custom code to run whenever a header is opened or closed
        //do nothing
    }
})
</script>