Exception 'org.postgresql.util.PSQLException' could not be instantiated

i have a problem to get a PSQLException. The reason is Hessian as transport layer. Hessian de-/serializes every Object automatically (Java Reflection) and needs for every object an standard constructor without parameters. your actual driver version don't includes a version of org.postgresql.util.PSQLException with a standard constructor without parameters.

The actual version of the driver i use is  8.4-701 JDBC 4 , the version of the database is version 8.3, the hessian version is 4.0.6, the JDK Version is 1.6.0_07, the eclipse version is 3.5.2  and the operating system is Mac OSX Version 10.6.3 (Snow Leopard).

Kind regards,