delete an attachment after service invocation

[Dario Di Minno]

I followed the instructions in the document "Fear of attachments" to 
write a client that sends an attachment.

  DataHandler dh = new DataHandler( new URL("file:///"+filename) 
);           
  server.addAttachment(dh);

After the invocation of the service I'd like the client to delete the 
file attached with:

attachedFile.delete();

but it always return false!

What's wrong in my class?

Thank you
Dario