Store counter in an oracle sequence

Question

I need an advice about the counter of incoming requests for Java ejb web service. Application server where a web service is deployed has 4 nodes, so the incoming request can be processed on any of 4, and I decided to store counter value in Oracle database. I set the current number of request by calling select SEQPACKSCYCLETOT.NEXTVAL from dual and it works fine.

But I also need to show current counter value, and here is a problem. When I call select SEQPACKSCYCLETOT.CURRVAL from dual sometimes I get an exception sequence SEQPACKSCYCLETOT.CURRVAL is not yet defined in this session.

What session is it about and how to work with it? Here is the code snippet:

@Singleton
public class DbWorkerImpl implements DbWorker {
@Override
public Long getPacksTotSeqValue() throws SQLException {
    String query = "select SEQPACKSCYCLETOT.CURRVAL from dual";
    Long packetsCount = null;
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try {
        conn = ds.getConnection(Username, Password);
        stmt = conn.createStatement();
        rs = stmt.executeQuery(query);
        if (rs.next())
            packetsCount = rs.getLong(1);
    } 
    catch (SQLException e) {
        logS.debug(this.servername + e.getMessage());
    }
    finally{
        if (rs!=null) rs.close();
        if (stmt!=null) stmt.close();
        if (conn!=null) conn.close();
    }
    return packetsCount;
}