WS2801 Questions?

hi everyone, lurker in forums, sort doubts other people mistakes , accomplishments, 1 messing me...

i have bought ws2801 rgb leds, , made circuit according schematic adafruit

and been reading datasheet looking @ code , stuff.
but im still not understanding.

so...
step 1: clk low more 500us
step 2: send 24 bits need 24 clock rising edges.
at 24 clocks change color.
my problem tests if send ff ff ff white color, on freaks out not lightning 1 of leds.
but if send ff ff fe works, cant attain last bit in duty ratio.
anyone care explain why?

thank time.

datasheet copy:
gray scale data word format , timing
clk pin keeps low more 500us make ws2801 internal status register reset, , @ moment, gray scale data in data shift registers latched.
now ws2801 ready gray scale data transport. when ws2801 receives total 24 clock rising edges, ws2801 enters relay mode, relays input signal got cki , sdi low distortion (100ps typical) , low delay time ( 8 ns typical). data format , timing diagram can seen in fig 11.
the gray scale data frame comprised of 3 gray data words, each data word composed of 8 gray scale data bits, total 24 bits.
the 8bit gray data can realize linear 256 led gray levels control.
during data transfer, first bit data frame signal, msb of rout channel, last 1 transferred
data shift register lsb of bout channel.
gray scale data 0000 0000 minimum 0 duty ratio, , 1111 1111 maximum 255/256 duty ratio.

Arduino Forum > Using Arduino > LEDs and Multiplexing > WS2801 Questions?

arduino