problem to get nextval of a sequence

Hi List

I try to get the 'nextval' of a sequence:
***
   String query = "SELECT nextval('nodes_nodeid_seq')";
   pstmt = conn.prepareStatement(query);
   logger.debug("statement: " + pstmt.toString());
   ResultSet ress = pstmt.executeQuery();
   long newID = ress.getLong("nextval");  // <-- Exception
***

I get the following Exception:
***
org.postgresql.util.PSQLException: ResultSet not positioned properly,
perhaps you need to call next.
    at
org.postgresql.jdbc2.AbstractJdbc2ResultSet.checkResultSet(AbstractJdbc2ResultSet.java:2380)
    at
org.postgresql.jdbc2.AbstractJdbc2ResultSet.getString(AbstractJdbc2ResultSet.java:1821)
    at
org.postgresql.jdbc2.AbstractJdbc2ResultSet.getFixedString(AbstractJdbc2ResultSet.java:2326)
    at
org.postgresql.jdbc2.AbstractJdbc2ResultSet.getLong(AbstractJdbc2ResultSet.java:1935)
    at
org.postgresql.jdbc2.AbstractJdbc2ResultSet.getLong(AbstractJdbc2ResultSet.java:2158)
    at org.daniel.pws.store.PostgresStore.newNode(PostgresStore.java:307)
    at org.daniel.pws.store.StoreTester.main(StoreTester.java:71)
2004-12-28 13:41:57,983 - not able to get the new nodeID
****

executing the query in PostgresSQL directly works, I get the correct
return value.
The Query itself seems to be executet, as I get other exceptions if I
misspell the columnname (e.g.).
I'm working with Postgres-jdbc: pg80b1-1.308.jdbc3.jar and JDK 1.5.0

someone an Idea?

wishing all a Happy new Year
Daniel