function CheckDates(sender,args)
{
    if(!document.getElementById('r4').checked)
    {
        var date1 = $find("ce1").get_selectedDate();
        var date2 = $find("ce2").get_selectedDate();
        
        if(date1 >= date2)
        {
            __doPostBack('butCheckDates','')
        }
    }
}