function valida_envia(){

    //name validation, just check for the field isn't empty
    if (document.fvalida.username.value.length==0){
       alert("You must type your PIN number")
       document.fvalida.username.focus()
       return false;
    }
	
	//password validation, just check for the field isn't empty
	if (document.fvalida.password.value.length==0){
       alert("You must type your password")
       document.fvalida.password.focus()
       return false;
    }

    //document.fvalida.submit();
	return true;
}