using iPad as soundboard through a mixer into garageband

I have my iPad connected to my Zedi 10 FX mixer going into ST1, but garageband only lets me select either input 1-2-3 or 4 or various combos of them and I'm not getting any level of the clips I'm playing on my soundboard. I hear them in my headphones but they aren't showing up in garageband.

Any help would be appreciated.