It's strange. Please make sure you update the DLL references in your VS project and recompile your project.
Can you try the following code?
<%@ Page Language="C#"%>
<%@ Register TagPrefix="CE" Namespace="CuteEditor" Assembly="CuteEditor" %>
<html>
<head>
<title>ASP and ASP.NET WYSIWYG Editor - Default Configuration </title>
<link rel="stylesheet" href="../example.css" type="text/css" />
</head>
<body>
<form runat="server">
<h2>Default Configuration</h2>
<CE:Editor id="Editor1" EditorWysiwygModeCss="../example.css" EncodeHiddenValue="false" runat="server" ></CE:Editor><br />
</form>
</body>
</html>
asp.net Chat http://cutesoft.net/ASP.NET+Chat/default.aspx
Web Messenger: http://cutesoft.net/Web-Messenger/default.aspx
asp.net wysiwyg editor: http://cutesoft.net/ASP.NET+WYSIWYG+Editor/default.aspx
asp wysiwyg html editor: http://cutesoft.net/ASP
asp.net Image Gallery: http://cutesoft.net/ASP.NET+Image+Gallery/default.aspx
Live Support: http://cutesoft.net/live-support/default.aspx