Presonus Audiobox USB Audio Interface Problem - Please Help

I'm new to recording and have got a very basic home recording studio set up. I have my guitar and bass playing (obviously) guitar and bass and then a keyboard i use for drums. Have not purchased mics yet. I have those going into a 6 channel Peavey Mixer. The left and right main outs go into the 2 inputs of the audiobox and the control room left and right go to 2 guitar amplifiers i'm using as temporary monitors until i get actual studio monitors. From there the audiobox goes into the usb port on my macbook. Now the problem: When I select the audio interface as the audio input setting, it says "no input controls". But then when i got and play something, garage band tracks the signal. it shows the sound levels go up and down (i don't know the technical term). but when i go to play it back nothing happens. I have the built in computer speaker selected as the audio output. Now to whoever cared enough to read this far, thank you very much. I know this is a long message, but I have been troubleshooting constantly for days and am totally lost as to what might be causing the problem. so i thought it'd be best to describe in detail my whole setup so y'all would know the whole situation. thanks.