I have tested your code and it appears to be working fine.
Why do not you want to use .cascade() method? I would extremely reduce validation code.
Example
<%@ Page Language="C#" %>
<%@ Register Assembly="Ext.Net" Namespace="Ext.Net" TagPrefix="ext" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Ext.Net Example</title>
<script type="text/javascript">
var validate = function (container) {
container.myIsValid = true;
container.cascade(
function (c) {
if (c.isValid) {
this.myIsValid = c.isValid();
}
},
container);
alert(container.myIsValid);
}
</script>
</head>
<body>
<form runat="server">
<ext:ResourceManager runat="server" />
<ext:Panel ID="Panel1" runat="server">
<Items>
<ext:NumberField runat="server" AllowBlank="false" />
<ext:TextField runat="server" AllowBlank="false" />
<ext:Panel runat="server">
<Items>
<ext:NumberField runat="server" AllowBlank="false" />
<ext:TextField runat="server" AllowBlank="false" />
<ext:Panel runat="server">
<Items>
<ext:NumberField runat="server" AllowBlank="false" />
<ext:TextField runat="server" AllowBlank="false" />
</Items>
</ext:Panel>
</Items>
</ext:Panel>
</Items>
</ext:Panel>
<ext:Button runat="server" Text="Validate">
<Listeners>
<Click Handler="validate(Panel1)" />
</Listeners>
</ext:Button>
</form>
</body>
</html>