Problem Using Zoom H4 as an Audio Interface with Garageband

I'm new to GB and I am having problems getting started using my Zoom H4 as an Audio Interface with Garageband on my iMAC.

I'm fairly certain that I have the connection and all of the setting configurations correct, and yet I cannot get any sound from the H4 into GB.

I do see the sound volume registering in the Input Level window of the H4, but not in GB.

Here is what I see in my Garageband:
Preferences >
Audio/MIDI >
- System Setting
- Built-in Microphone
- Built-in Input
- H4 Audio IN (when H4 is connected to the iMAC via USB)

Of course I have selected the H4.

Any help or insight would be greatly appreciated. Operators standing by!
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