R-2.6.0 package check problems

Hello


One of my packages, untb_1.3-2, passes R CMD check under
MacOSX (and apparently the systems used in the package check
summary page on CRAN) but fails with the following message on
R-2.6.0.tgz compiled last night on my (home) linux box.  I hasten
to add that I have never seen this error before on home-compiled
pre-releases of R-2.6.0.

Can anyone help me understand what is going on?

localhost:~/scratch%R CMD check untb_1.3-2.tgz

[snip]

creating untb-Ex.R ... OK
* checking examples ... ERROR
Running examples in 'untb-Ex.R' failed.
The error most likely occurred in:

 > ### * butterflies
 >
 > flush(stderr()); flush(stdout())
 >
 > ### Name: butterflies
 > ### Title: abundance data for butterflies
 > ### Aliases: butterflies butterfly
 > ### Keywords: datasets
 >
 > ### ** Examples
 >
 > data(butterflies)
 > plot(butterflies, uncertainty=TRUE)

Error in log(theta) :
   could not find symbol "base" in environment of the generic function
Calls: plot ... optimal.theta -> optimize -> <Anonymous> -> f -> log
Execution halted







localhost:~/scratch%R

 > sessionInfo()

R version 2.6.0 (2007-10-03)
i686-pc-linux-gnu

locale:
LC_CTYPE=en_US;LC_NUMERIC=C;LC_TIME=en_US;LC_COLLATE=en_US;LC_MONETARY=e 
n_US;LC_
MESSAGES=en_US;LC_PAPER=en_US;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_M 
EASUREME
NT=en_US;LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] rcompgen_0.1-15

 > R.version

                _
platform       i686-pc-linux-gnu
arch           i686
os             linux-gnu
system         i686, linux-gnu
status
major          2
minor          6.0
year           2007
month          10
day            03
svn rev        43063
language       R
version.string R version 2.6.0 (2007-10-03)

 >
 >

--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743