Loosing steps with Gecko 340 drive

Hi
I'm having an interesting problem. I've been playing around with
Arts Mach1 program. I noticed I was loosing steps when I ran
some programs but not others. Art suggested that I lower the
acceleration and sure enough no more lost steps. My question
is If Mach1 was delivering steps at a faster rate than the servos
could handle why didn't the Geckos fault out?


Thanks
Derek