My comment on Audio drivers was caused by your statement "The Midi/Audio drivers setup shows the Keystation 88 for input."
Have you got Realtracks (meaning audio) to play back and work OK?
Another question; when you try to play, what channel do you have selected in BiaB?
Question 2 - What channel is the keyboard sending MIDI on?
Does the Synth channel match the track's selected MIDI channel?
FWIW I'm pretty sure I could get you working in RB .. I don't try much in BiaB other than trying out styles/chords .. then it's off to RB pretty quickly here.
More intuitive for me.
Can you simply connect the audio from the keyboard to the audio in on the computer?
That would be easiest.
Also, others know more, but I *think* MIDI thru is channel 4 or 5 on BiaB.
Also, very related thread:
http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=384248&page=3