function validate_login(){
	var username = document.getElementById('txtUsername');
	var password = document.getElementById('txtPassword');
	var error = 0;
	if(username.value==""){
		username.setAttribute('className', 'inputError')
		error = 1;
	}
	if(password.value==""){
		password.setAttribute('className', 'inputError')
		error = 1;
	}
	if(error == 0){
		return true;
	}else{
		alert("Error! Please correct your username and password");
		return false;
	}
}