function validate_callback()
{
	name1=document.getElementById('name');
	phone=document.getElementById('telephone');
	hour=document.getElementById('time-hour');
	minutes=document.getElementById('time-minutes');
	if (name1.value=='')
	{
		alert("Please enter your name.");
		name1.focus();
		return false;
	}
	if (phone.value=='')
	{
		alert("Please enter your phone number.")
		phone.focus();
		return false;
	}
	if (hour.selectedIndex == 0)
    {
        alert("Please select your preferred hour.");
        hour.focus();
		valid = false;
		return false;
    }
	if (minutes.selectedIndex == 0)
    {
        alert("Please select your preferred minutes.");
        minutes.focus();
		valid = false;
		return false;
    }
	return true;	
}