I tried to use CloudScape 5.1.60.17 driver which comes with IBM WebSphere Application Server - Express 6.0 from the IDE and failed. There are two drivers - to use locally on the same machine with the DB server and another one to use through the network. The latter one works, the former one fails.

Steps to reproduce:
- Install IBM WebSphere Application Server - Express 6.0
- Run IDE
- Right-click Databases > Drivers node and select Add Driver in Runtime window
- Add %WEBSPHERE_INSTALL_DIR%/cloudscape/lib/db2j.jar driver file
- Click Find Driver
- Select com.ibm.db2j.jdbc.DB2jDriver as Driver Class
- Name it "CloudScape Driver" and click OK
- Create New Database using CloudScape cview tool (Don't forget to shutdown the database)
- Try to connect to it using CloudScape Driver using URL of form "jdbc:db2j:%DATABASE_DIR%"
- Click OK - The wizard successfully connects and reads schemas name.
- Select APP schema and click OK
- RESULT: Unable to add connection error dialog is shown. It seems that IDE obtained lock to this DB and lost it. Until you restard IDE you will not be able to connect to this DB using any of drivers cause the DB would be in use.

The workaround is to use Network version of driver, but I have no idea why the former driver doesn't work