Any idea what is wrong here?

import sysimport pygstpygst.require("0.10")import gstimport pygtkimport gtkclass Munger:        def __init__(self, outfile, callback):                #self.source_count = 0        self.complength = 0L        self.finished = callback        # make a pipeline        self.pipeline = gst.Pipeline("mypipeline")                self.bus = self.pipeline.get_bus()        self.bus.add_signal_watch()        self.bus.connect('message', self._on_eos)        # creating a gnlcomposition        self.comp = gst.element_factory_make("gnlcomposition", "mycomposition")        self.pipeline.add(self.comp)        self.comp.connect("pad-added", self._on_pad)        # create an audioconvert        self.compconvert = gst.element_factory_make("audioconvert", "compconvert")        self.pipeline.add(self.compconvert)        self.resample = gst.element_factory_make('audioresample')        self.pipeline.add(self.resample)        caps = gst.caps_from_string('audio/x-raw-int, rate=44100, channels=2, endianness=1234, width=16')        self.capsfilter = gst.element_factory_make("capsfilter")        self.pipeline.add(self.capsfilter)        self.capsfilter.set_property("caps", caps)        # create encoder and muxer        self.queue = gst.element_factory_make('queue')        self.pipeline.add(self.queue)        self.enc = gst.element_factory_make('vorbisenc')        self.mux = gst.element_factory_make('oggmux')        self.pipeline.add(self.enc, self.mux)        # create a filesink        self.sink = gst.element_factory_make("filesink", "filesink")        self.sink.set_property('location', outfile)        self.pipeline.add(self.sink)        # link up elements        gst.element_link_many(self.compconvert, self.enc, self.queue, self.mux, self.sink)            def add_source(self, file):        # File must be an AudioFile instance!!!                # create a gnlfilesource        #sourcename = 'source' + str(self.source_count)        source = gst.element_factory_make("gnlfilesource")        # set the gnlfilesource properties        source.set_property('location', file.path)        source.set_property('start', self.complength)        source.set_property('duration', file.duration)        source.set_property('media-start', 0L)        source.set_property('media-duration', file.duration)        self.comp.add(source)        # add to total composition length        self.complength += file.duration        print self.complength        # increase source count        #self.source_count += 1            def _on_pad(self, comp, pad):        convpad = self.compconvert.get_compatible_pad(pad, pad.get_caps())        pad.link(convpad)            def start(self):        print 'Total length: %d' % self.complength        self.pipeline.set_state(gst.STATE_PLAYING)            def _on_eos(self, bus, message):        if message.type == gst.MESSAGE_ERROR:            gerror, debug = message.parse_error()            print 'DEBUG: Error. Ouch.'            print 'DEBUG: ' + gerror            print 'DEBUG: ' + debug            self.finished()        elif message.type == gst.MESSAGE_EOS:            self.finished()        print message