function check_valid()
{
	if(document.freight.number.value=='')
	{
		alert("Please enter the container number");
		document.freight.number.focus();
		return false;
	}

	if (document.freight.shipper.selectedIndex == "")  
	{
		alert ("Kindly select type of tracking the container.");
		document.freight.shipper.focus();
		return false;
	}

	return true;
}