Java Database Connectivity (JDBC)

Hi,

I have problems to connect to an InterBase 6.5 database.
My code is the following :

...
try {
      DataBaseConnect dbC = new DataBaseConnect();
    }
    catch (Exception e)
    {
      System.out.println (e.toString());
    }
....
public class DataBaseConnect {
    private Statement stmt;
    private Connection forb;
    public DataBaseConnect() throws Exception {
      Class.forName("interbase.interclient.Driver");
      forb = DriverManager.getConnection("jdbc:interbase://127.0.0.1/D:/TESTDB.GDB","SYSDBA", "masterkey");
      stmt = forb.createStatement();
    }
  }

I obtain the following error message :
"java.lang.VerifyError: (class: interbase/interclient/ErrorKey, method: _$372 signature: (Ljava/lang/String;Ljava/lang/String;I)V) Expecting to find unitialized object on stack"

In fact, I don't know if I have the good version of InterClient, that I downloaded at the following address :
http://info.borland.com/devsupport/interbase/opensource/#ibtools

However, the CLASSPATH variable is pointed on interclient.jar, so I don't know where the problem is ?

Thanks for any answer.