Libao, too many arguments to function ao_play()

I am working on wrapping libao in Ruby and I ran into an issue that probably is a big in my code (I am not a good C programmer). I get the following make error message referring to the method that wraps a call to ao_play():

gcc -I. -I. -I/usr/lib/ruby/1.8/i686-linux -I. -D_FILE_OFFSET_BITS=64 -fPIC -march=i686 -mtune=generic -O2 -pipe -fPIC -c audiolibs.c audiolibs.c: In function ‘play_ao’: audiolibs.c:56: error: expected expression before ‘ao_device’ audiolibs.c:56: error: too few arguments to function ‘ao_play’ make: *** [audiolibs.o] Error 1

I am running Arch Linux (Linux ghostintheshell 2.6.30-ARCH #1 SMP PREEMPT Fri Jul 31 18:10:38 UTC 2009 i686 Intel(R) Core(TM)2 CPU 6420 @ 2.13GHz GenuineIntel GNU/Linux) with extra/libao 0.8.8-2, core/make 3.81-4, and core/gcc 4.4.1-1 installed.

I have attached a few relevant files. Maybe you have an idea of what is going on. Any help that you provide will be much appreciated. Thanks for you time.