//This requires that the property NamingContainerId is set on the
//validation object in the code behind by using the: ClientScriptManager..::.RegisterExpandoAttribute Method
var radioValidationHelper = {

    //ensure there is more than 0 radio buttons checked.
    DoValidate: function(sender, args) {
        args.IsValid = $("#" + sender.NamingContainerId + " .radioButtons input:checked").val() != undefined && $("#" + sender.NamingContainerId + " .radioButtons input:checked").val().length > 0;
    }

}