Now its working (Code below) ,But If I put ReadOnly=true it is not working?
I found one more thing, Sometimes It is giving property/method does not support still.
I put this code in aspx body.
<script language="JavaScript" type="text/javascript" >
var editor1=document.getElementById("<%=Preview.ClientID%>");
if(editor1.IsReady)CuteEditor_OnInitialized(editor);
function CuteEditor_OnInitialized(editor)
{
editor1.ExecCommand(
"ZOOM",false,20);
}
</
script>