you can try the embeded sql manager, with your browser point to :
localhost:8080/jmx-console, then go in the mbean for hsqdb, there is a "start manager" operation that will open a swing GUI that manages HSQLDB.
Where you see the error message, click the 'More' button to get a stack trace of what actually went wrong. Copy and paste that here. It might say "Driver not found" or it might say you have a permissions problem connecting to the database. Or something else entirely.