Cannot create JDBC driver of class 'org.apache.derby.jdbc.EmbeddedDriver' for connect URL 'jdbc:derby:...'

[Clemens Wyss]

I am trying to open an existing sling jackrabbit repository.

My code is as follows:
...
String configURLObj = "file:/C:/dev/sling/sling/jackrabbit/repository.xml";
URL configURL = new URL(configURLObj);
InputStream ins = configURL.openStream();
String home = "/dev/sling/sling/jackrabbit";
RepositoryConfig crc = RepositoryConfig.create( ins, home );
//RepositoryConfig crc = RepositoryConfig.create( new 
File("/dev/sling/sling/jackrabbit") );
Repository repository = RepositoryImpl.create( crc );
...

or

...
RepositoryConfig crc = RepositoryConfig.create( new 
File("/dev/sling/sling/jackrabbit") );
Repository repository = RepositoryImpl.create( crc );
...

Unforunately I am getting a
  javax.jcr.RepositoryException: Cannot instantiate persistence manager
  org.apache.jackrabbit.core.persistence.db.DerbyPersistenceManager

with the nested SQLNestedException
  Cannot create JDBC driver of class 'org.apache.derby.jdbc.EmbeddedDriver'
  for connect URL 
'jdbc:derby:/dev/sling/sling/jackrabbit/version/db;create=true'

Also note
- jackrabbit-standalone-2.1.1.jar and derby-10.5.3.0_1.jar are in build/run path
- sling is not ruuning ;-)
- lock files are deleted ;-)

Any help/advice appreciated
Clemens