I assume you are working with Standard Engine. Do you have a version of the product?
A few known issues for v5 and v7, but I think you are hitting this one:
THE JDBC DRIVER IS UNABLE TO CONNECT TO STANDARD ENGINE UNLESS THE DATABASE RESIDES IN THE CONNECTING USER'S
HOME DIRECTORY OR A SUBDIRECTORY.
A possible workaround for this is to create a symbolic link in the users home directory to the database. Another workaround would be to pass DBPATH variable in your url. Set DBPATH to the location of the database.