htmlEditorExtender not showing property on server but working properly in local machine

html Editor Extended property not showing on server but in local machine working properly i think this error because of script manager not working properly here is the code

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="Acc" %>
<asp:ScriptManager ID="ScriptManager" runat="server"></asp:ScriptManager>

  <asp:TextBox ID="txtContent1" runat="server" Width="300" Height="200" TextMode="MultiLine" />
<Acc:HtmlEditorExtender ID="HtmlEditorExtender2" runat="server" TargetControlID="txtContent1" EnableSanitization="false" DisplaySourceTab="True">