Timeout error accesing MySql RDS from a Lambda function

Hi,

I have a problem connecting from a lambda function with a RDS MySql database.
I try to follow the tutorial http://docs.aws.amazon.com/lambda/latest/dg/vpc.html , but when I try to connect with the database, the lambda function return allways a timeout error. I have tried with several roles and security groups... but I have achieved nothing.
I think I'm doing something wrong... please help me.

I have a function for test:

//loading required modules;
console.log('Loading function');
var mysql= require('mysql');
//This handler will invok after receiving the event with username,password and status
module.exports.testeo = function(event, context, callback) {
	var conn = mysql.createConnection({
	  host     : 'xxxxxxx.eu-west-1.rds.amazonaws.com',
	  user     : 'xxxxxxx',
	  password : 'xxxxxxx',
	  database : 'xxxxxxx'
	});
	conn.connect(function(err) {  // creating database connection
  		if (err) {
	    console.error('error connecting: ' + err.stack); // on error
		return;
		}
	    console.log('connected as id ' + conn.threadId);
	});
console.log("ok");	   
};

In the lambda funtion I have this configuration:

• Role: miclub-beta-eu-west-1-lambdaRole (with policies: AmazonLambdaVPCAccessExecutionRole, AmazonRDSFullAccess, AmazonRDSDirectoryServiceAccess)
• VPC: vpc-c84ec6af(172.30.0.0/16)
• Subnets: subnet-9e7af9f9 (172.30.0.0/24) | eu-west-1a ; subnet-ecba31a5 (172.30.1.0/24) | eu-west-1b ; subnet-4700cf1c (172.30.0.0/24) | eu-west-1c
• Security groups: sg-1626b96e (default) (Inbound rules: ports: All sources: sg-1626b96e; Outbound: Ports: All destination: 0.0.0.0/0)

In the RDS Instance I have this configuration:

• Multi-AZ Deployment: No
• Security group: default (sg-1626b96e) (vpc-c84ec6af)
• Publicly Accesible: Yes
• Enable IAM DB Authentication: No

I can access to the RDS from external IPs without problems... but I can't access from lambda functions.
Please... what is wrong?