function IsValidTime(timeStr)
{
	var timePat = /^(\d{1,2}):(\d{2})(:(\d{2}))?(\s?(AM|am|PM|pm))?$/;
	var matchArray = timeStr.match(timePat);
	if (matchArray == null) 
	{
		alert("Time is not in a valid format.");
		return false;
	}
	hour = matchArray[1];
	minute = matchArray[2];
	second = matchArray[4];
	ampm = matchArray[6];

	if (second=="")
	{
		second = null;
	}
	if (ampm=="") 
	{	
		ampm = null
	}
	if (hour < 0  || hour > 12)
	{
		alert("Hour must be between 1 and 12");
		return false;
	}
	if(hour <= 12 && ampm == null)
	{
		alert("You must specify AM or PM.");
		return false;
   		
	}
	if  (hour > 12 && ampm != null)
	{
		alert("Time is not in a valid format.");
		return false;
	}
	if (minute<0 || minute > 59)
	{
		alert ("Minute must be between 0 and 59.");
		return false;
	}
	if (second != null && (second < 0 || second > 59))
	{
		alert ("Second must be between 0 and 59.");
		return false;
	}
	return false;
}