JDeveloper

Apologies in advance if this isn't quite the correct forum to post this
question in. but I thought it might be more appropriate than a posting
to general. I am evaluating Oracles JDeveloper 10g and want to use
postgres as the database but it doesn't want to work. Google results
show that it is possible but I haven't found the details on how to
configure it.

database - postgresql 7.4.2 on debian
java ide - jdeveloper 10g on windows 2000

In jdeveloper I'm trying to create a new database connection
-> Connection Type: Third Party JDBC Driver
-> username: postgres pasword: mypassword
-> Driver Class: org.postgresql.Driver
-> Classpath: c:\pg74.215.jdbc2.jar
-> Source Path: c:\pg74.215.jdbc2.jar
and then I run Test Connection:
 java.lang.NullPointerException

Of course any help or insight is gratefully accepted.

Thanks
Ron