aspx element visibility ould not find
// Server-side:
Panel1.Style.Add("display", "none") to hide
Panel1.Style.Add("display", "") to show
//Client-side:
<script type="text/javascript">
// hide
document.getElementById('<%= Panel1.ClientID %>').style.display = 'none')
// show
document.getElementById('<%= Panel1.ClientID %>').style.display = '')
</script>