Can't edit in tinymce editor.Textarea cannot enter.

<div class="main_body">
<form id="sform" action="product-add.php" method="post" enctype="multipart/form-data">
<table class="inputform" cellpadding="1" cellspacing="1">
<td class="label">title</td><td class="input"><textarea class="txt" name="productdescription" style="width:200px;height:110px;"></textarea></td>
<td class="label">product</td><td class="input"><textarea id="contentform" rows="1" cols="1" style="width:580px;height:360px;" name="productcontent"></textarea>
<!-- Load TinyMCE -->
<script type="text/javascript" src="tiny_mce/jquery.tinymce.js"></script>
<script type="text/javascript" src="tiny_mce/plugins/swampy_browser/sb.js"></script>
<script type="text/javascript">
		$().ready(function() {
				$("#contentform").tinymce({
						// Location of TinyMCE script
						script_url : 'tiny_mce/tiny_mce.js',

						// General options
						theme : "advanced",
						language : "zh",
						width : "580",
						height : "360",
						add_unload_trigger : true,
						plugins : "Ybrowser,pagebreak,style,layer,table,save,advhr,advimage,advlink,emotions,iespell,inlinepopups,insertdatetime,preview,media,searchreplace,print,contextmenu,paste,directionality,fullscreen,noneditable,visualchars,nonbreaking,xhtmlxtras,template,advlist",

						// Theme options
						theme_advanced_buttons1 : "undo,redo,|,bold,italic,underline,strikethrough,|,justifyleft,justifycenter,justifyright,justifyfull,formatselect,fontselect,fontsizeselect",
						theme_advanced_buttons2 : "forecolor,backcolor,del,ins,|,cut,copy,paste,pastetext,pasteword,|,outdent,indent,attribs,|,link,unlink,anchor,image,Ybrowser,media,cleanup,|,preview,code,fullscreen",
						theme_advanced_buttons3 : "",
						theme_advanced_buttons4 : "",
						theme_advanced_toolbar_location : "top",
						theme_advanced_toolbar_align : "left",
						theme_advanced_statusbar_location : "bottom",
						theme_advanced_resizing : false,
					   
						// Drop lists for link/image/media/template dialogs
						template_external_list_url : "lists/template_list.js",
						external_link_list_url : "lists/link_list.js",
						external_image_list_url : "lists/image_list.js",
						media_external_list_url : "lists/media_list.js"
				});
				var formoptions = {
						beforeSubmit: function() {
								$("#submitbtn").val("doing...");
								$("#submitbtn").attr("disabled","disabled");
						},
						beforeSerialize: function($form, options) {
								tinyMCE.triggerSave();				
						},
			success: function (msg) {
				alert(msg);
								if(msg == "fishing")
										$("#sform").resetForm();
								$("#submitbtn").val("submit");
								$("#submitbtn").attr("disabled","");
			}
		};
				$("#sform").ajaxForm(formoptions);
				$("#pubdate").datetimepicker({
						showSecond: true,
						timeFormat: 'hh:mm:ss',
						hour:16,
						minute:43,
						second:26,
						closeText:'complete',
						currentText:'TIME'
				});
		});
</script>
<!-- /TinyMCE -->
</td></tr>
</table>