nprocreg didn't start with mochiweb backend

error occurs when calling functions that work with the session (wf:user, wf:session, etc)

=INFO REPORT==== 29-Jun-2010::23:29:37 ===
{error,exit,
    {noproc,
        {gen_server,call,
            [nprocreg,
             {get_node,
                 {session,

<<204,247,25,128,203,73,179,49,154,114,83,130,167,36,
                       38,62>>}}]}},
    [{gen_server,call,2},
     {nprocreg,get_pid,2},
     {nprocreg_registry_handler,get_pid,4},
     {wf_handler,call,3},
     {process_registry_handler,get_pid,2},
     {simple_session_handler,get_session_pid,2},
     {simple_session_handler,get_value,4},
     {wf_handler,call,3}]}

I changed the line: application: start(mprocreg) to application: start(nprocreg) in file: ./Nitrogen/site/src/nitrogen_init.erl and the error disappeared