uC/OS, LWIP and fdopen

I'm trying to use fdopen to convert an LWIP socket FD to a stream. I get no errors, but It doesn't seem to work...

    int newFd = accept (sFd, &client, &saddrsize);
      
    if (newFd != ERROR)
   {      
      FILE * tout = fdopen(newFd,"w");
      fprintf(tout,"Hello world\r\n");
   }

standard recv/send on the socket works just fine - anyone seen this?

- Roddy