<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Default" %>

<!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></title>
    <telerik:RadStyleSheetManager ID="RadStyleSheetManager1" runat="server" />
</head>
<body>
    <form id="form1" runat="server">
    <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
    </telerik:RadScriptManager>
    <script type="text/javascript">
        function validating(sender, eventArgs) {
            var tb = $find("<%= RadInputManager1.ClientID %>").get_targetInput("<%= TextBox1.ClientID %>");
            //perform your custom check 
            if (tb.get_value().indexOf('9') < 0) {
                tb.get_owner()._inputs[tb._id]._invalid = true;
                tb.updateCssClass();
            }
        }

    </script>
    <div>
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <telerik:RadInputManager ID="RadInputManager1" runat="server">
            <telerik:RegExpTextBoxSetting ClientEvents-OnValidating="validating" ValidationExpression="[0-9]{6,}">
                <TargetControls>
                    <telerik:TargetInput ControlID="TextBox1" />
                </TargetControls>
            </telerik:RegExpTextBoxSetting>
        </telerik:RadInputManager>
    </div>
    </form>
</body>
</html>
