function champVide() 
{ 
	var alerte; 
	alerte = ''; 
	if (document.auth.username.value.length == 0)
	{
		if(document.auth.password.value.length == 0)
		{ 
			alerte = 'You must enter your username and your password.\n'; 
			alert(alerte);
			return false; 
		}
		else
		{
			alerte = 'You must enter your username.\n';
			alert(alerte);
			return false; 
		}
	}       
	else
	{
		if (document.auth.password.value.length == 0) 
		{ 
			alerte = 'You must enter your password.\n'; 
			alert(alerte);
			return false; 
		}
		else
		{
			return true;
		}
	}          
};