OK here is code : Ziu z = new Ziu(); Class.forName("org.postgresql.Driver"); db = DriverManager.getConnection(url, usr, pwd); Serialize.create((org.postgresql.Connection) db,z.getClass()); Serialize s = new Serialize((org.postgresql.Connection) db, Serialize.toPostgreSQL( z.getClass().getName() ) ) ; //and here i have Exception described below int oid = s.store(z); Ziu zz = (Ziu ) s.fetch(oid); ============================ Exception in thread "main" java.lang.NullPointerException at org.postgresql.jdbc2.ResultSet.getString(ResultSet.java:148) at org.postgresql.util.Serialize.create(Serialize.java:241) at Test.main(Test.java:31) ============================ Please I need help with that !!!! Why is the Exception , what should I do to avoid that (...) Exception! -- MS is not the answer. MS is the question. NO (or Linux) is the answer. :) Jarek (: ------------------------------------------------------- -- MS is not the answer. MS is the question. NO (or Linux) is the answer. :) Jarek (: