Oracle CQN Issue

I am facing the below problem:

Both my DB server and Application server have full duplex connection. But I am not getting any notifications or error. I am using :

    oracledb: 5.3.0
    Node version : 12.2.2
    oracle DB : 19 C
    oracle client : 12.2
    server : linux

Below is my code:

function myCallback(message) {
    console.log(`Listened new data insertion`);

    //Calling a function
    postMessage();
}


const options = {
    callback: myCallback,
    sql: `SELECT ID FROM tableName where user_id = 0`,
    qos: oracledb.SUBSCR_QOS_ROWIDS,
    clientInitiated: true

};

async function listener() {
    let connection;
    try {

        connection = await oracledb.getConnection({
            user: `${userName}`,
            password: `${userPass}`,
            connectString: `${connString}`,
            externalAuth: false,
            events: true
        });

        await connection.subscribe('mysub', options);
        console.log("App is Listening To table");

    } catch (err) {
        console.log("Error on Listening" + err);
    }

}