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>