function valid_userform()
{
	if(document.demo.username.value=="")
	{
		alert("Please, Enter Your User ID.");
		document.demo.username.focus();
		return false;
	}
	else if(document.demo.password.value=="")
	{
		alert("Please, Enter Your Password.");
		document.demo.password.focus();
		return false;
	}
	else
	{
		return true;
	}
}