Error connection to Oracle database with DJBC driver

Hi everybody

I have issue with datadirect driver connection to Oracle 12c via IPv4.

I have web application for tomcat. This application it trying to connect to database.

String driver = "com.asg.jdbc.oracle.OracleDriver";
String url = "jdbc:asg:oracle://usdenmsx3.asg.com:1521;ServiceName=orasun12";
String name = "tcitest";
String password = "tcitest1";

Class theClass = Class.forName(driver);

PrintWriter log = new PrintWriter(System.out, true);
DriverManager.setLogWriter(log);
DriverManager.registerDriver((Driver) theClass.newInstance());

Connection connection = DriverManager.getConnection(url, name, password);

This application is working properly and return Connection.

ALso I have another application whic is more complicated and has the same code. But second application is return an error
java.sql.SQLNonTransientConnectionException: [ASG][Oracle JDBC Driver]Error establishing socket to host and port: usdenmsx3.asg.com:1251. Reason: Connection refused: connect

How can I recognize what the problem with?