Cant hear song playback while recording with external USB Interface Mic in Garageband

Hi there

There must be something wrong with my settings in Gargaeband/Mac Sound Settings.

I have Garageband 9 (V5.1) running a song I have already recorded using a USB keyboard.

I want to record using my external mic and my USB Audio Interface, so

I select New Track> Real Instrument

I plug in my Yamaha Audiogram 3 USB AUdio Interface and I get a pop up stating

"Garageband is scanning your system for audio devices, and has detected a device named "USB Audio Codec"

If you want to use this device do not disconnect it during the scanning process.

Do you want to use this devise No/Yes."

I select Yes and INPUT SOURCE changes from

Mono 1 (Built-in Microphone)

to

Mono 1 (USB Audio CODEC)

I can see the signal lights lighting up on the audiogram 3 when I talk into the mic, so theres no problem there.

Also when I hit record I can record audio using the mic, and can see the levels (and the audio wave I am creating being drawn on the screen) but I cannot hear the track itself when I am recording using the mic. Nor can I hear the track or the new mic recorded audio AFTER I have hit stop.

The only way to hear the song again with the newly recorded mic track is to unplug the Audiogram 3 (Then I get another Pop-up stating

"The audio device "USB Audio CODEC" has been disconnected!

Do you want to switch to Built-in Audio or quit Garageband?"

I select USE BUILT-IN AUDIO)

Then the input source changes back to

Mono 1 (Built-in Microphone)

And I can hear the track again.

So my problem as you can see if that I cant hear the track while recording using the microphone with the Audiogram 3.

But I can record video with audio using the audiogram 3 USB Audio Inteface and mic using photobooth when I select change Sound>Input to USB Audio Codec in system preferences

It therefore assume it must be a problem with the internal audio settings of the mac/garageband.

Can anyone advise?

thanks!