Session time zone not set?

I am attempting to query a table that has a data type 'TimeStamp with local time zone'. however when I attempt to do so SoapUI is returning the following error, Thu May 19 09:19:52 CDT 2011:ERROR:java.sql.SQLException: Session Time Zone not set!

Does anyone know where this can be set? I've check the system properties, attempted an alter session on the db app, but nothing. Thanks.