[BioC] chromosome plot

[yanju]

Dear all,

I was trying to visualize genes in each chromosomes in Zebrafish. I 
found how people visualize them in Human species using geneplotter. Then 
I tried followings:

 > library("annotate")
 > library("geneplotter")
 > library(zebrafish)
 > newChrom<-buildChromLocation("zebrafish")

then I got a error:
Error in get(x, envir, mode, inherits) : variable "zebrafishCHRLENGTHS" 
was not found

There is no zebrafishCHRLENGTHS variable which record the length of each 
chromosome in Zebrafish. What should I do?

Regards,
Yanju