ipfw: queue size must be < 4B

[Michael Spratt]

Hi when I load the following rule to create the pipe I get the following 
error
command:
ipfw pipe 1 config bw 128Kbit/s queue 3Kbytes mask dst-ip 0xffffffff
error:
ipfw: queue size must be < 4B

Can anyone tell me why? 

uname -a
Linux - 2.6.33.4 #3 SMP Wed May 12 23:13:09 CDT 2010 x86_64 Intel(R) 
Xeon(R) CPU           E5430  @ 2.66GHz GenuineIn NU/Linux

Its working on other similar Linux machines I have.  Any ideas?

Thanks -Mike