question

hello, i'm new to JDBC and i was trying to follow the instructions
on how to configure the postgresql jdbc driver on java. i'm using
j2sdk1.4.0 and i'm using j2re1.4.0. i was testing the connectivity of Java
to my Postgresql Server and it was able to connect successfully. The
problem is when I try to add the SQL statement below
       Statement st = con.createStatement();
       ResultSet rs = st.executeQuery("SELECT empno FROM personal ");
it generates this error:
     java.lang.NoSuchMethodError: java/sql/Statement.getResultSetConcurrency()I
        at org.postgresql.jdbc2.Connection.getResultSet(Connection.java:216)
        at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:121)
        at org.postgresql.Connection.ExecSQL(Connection.java:398)
        at org.postgresql.jdbc2.Statement.execute(Statement.java:130)
        at org.postgresql.jdbc2.Statement.executeQuery(Statement.java:54)
        at PGTest.main(PGTest.java:22)
 can you please tell me what could have been wrong. any help
 would be greatly appreciated.