gen_smtp.app.src problem

gistfile1.txt

==> rel (generate-upgrade)
ERROR: Systools aborted with: [{error_reading,
                                {gen_smtp,
                                 {{missing_param,registered},
                                  {application,gen_smtp,
                                   [{description,
                                     "An erlang SMTP server/client framework"},
                                    {vsn,"0.1"},
                                    {modules,
                                     [binstr,gen_smtp_client,gen_smtp_server,
                                      gen_smtp_server_session,mimemail,
                                      smtp_server_example,smtp_util,socket]},
                                    {applications,[kernel,stdlib]}]}}}}]