Garageband/USB Mixer volume issue

I recently bought a Behringer Xenyx 1622fx mixer to use with my garage band in order to record guitar, etc. However, when I record with garage band the volume is extremely low despite turning everything up all the way. Is there any remedy to this problem? When I play music however, from my Itunes through my mixer into headphones the volume is perfect, so I don't think it is a hardware issue. Is it most likely a mixer issue, or a garage band issue, or a mixture of the two. Thanks for the help!