If we use the following code:
// Navigate to : 'http://demos.kendoui.com/web/calendar/index.html'
ActiveBrowser.NavigateTo("http://demos.kendoui.com/web/calendar/index.html");
 
//Get the Calendar object
KendoCalendar calendar = ActiveBrowser.Find.ById<KendoCalendar>("calendar");
 
//Select date
calendar.selectDay("2013, 09, 18");

It will select 18th October 2013, not 18th September 2013. This is counterintuitive since in C#,  DateTime months are not Zero-based as they are in JavaScript Date Object.