AUGraph Record and Play with RemoteIO and MultiChannelMixer

i have a Problem ;)

i want to record Audio from the Mic and Write it to the Filesystem with Extended Audio File Services and also play the recorded Stuff. if i only use the remoteIO with two callbacks one for read one for write it works.

For the Volumen Control i want to use the MultiChannelMixer and the AUGraph. is it possible that you realize playback and recording with the same mixer and the RemoteIO?

i think it must look like this:

RemotIO Input   ->        -> Write Callback
                    Mixer
RemoteIO Output <-        <- Read Callback

i create two AUNodes (RemoteIO and MultiChannelMixer), how must i set the Callbacks and the Connections that one Callback deliver the AudioData from the mic and an other reads the Data from a File and both paths go through the mixer?

The reading and writing is not the Problem, only the configuration of the Nodes!

…and the output of CAShow:

AudioUnitGraph 0x8AEE000:
  Member Nodes:
    node 1: 'aumx' 'mcmx' 'appl', instance 0x865a510 O I
    node 2: 'auou' 'rioc' 'appl', instance 0x865d0a0 O I
  Connections:
    node   1 bus   0 => node   2 bus   0  [ 2 ch,  44100 Hz, 'lpcm' (0x0000000C) 16-bit little-endian signed integer]
    node   2 bus   1 => node   1 bus   1  [ 2 ch,  44100 Hz, 'lpcm' (0x0000000C) 16-bit little-endian signed integer]
  Input Callbacks:
    {0x4150, 0x7573340} => node   2 bus   1  [2 ch, 44100 Hz]
    {0x4330, 0x7573340} => node   1 bus   0  [2 ch, 44100 Hz]
  CurrentState:
    mLastUpdateError=0, eventsToProcess=F, isRunning=F

here is the setup code:

    OSStatus setupErr = noErr;

AudioComponentDescription mixerDescription;
AudioComponentDescription ioDescription;

// the AUNodes
AUNode mixerNode;
AUNode ioNode;

// the graph
setupErr = NewAUGraph(&_graph);
NSAssert(setupErr == noErr, @"Couldn't create graph");

// the mixer
mixerD