Please make sure you are using the correct SID in the Database URL. The following is the URL format you should use when configuring the JDBC data source:
jdbc:oracle:thin:@<host name>:<port>:<SID> (Example: jdbc:oracle:thin:@acme:1521:ORCL)
You can find more information about this topic in the "Importing JDBC Sources" section of the Virtual DataPort Administration Guide, and the "Parameters of the JDBC Connection URL" section of the Virtual DataPort Developer Guide.
Hope this helps!