Caret: Use timingSamps leads to error

I want to use the caret package and found out about the timingSamps
obtion to obtain the time which is needed to predict results. But, as
soon as I set a value for this option, the whole model generation fails.
Check this example:

-------------------------
library(caret)

tc=trainControl(method='LGOCV', timingSamps=10)
tcWithout=trainControl(method='LGOCV')

x=train(Volume~Girth+Height, method="lm", data=trees, trControl=tcWithout)

x=train(Volume~Girth+Height, method="lm", data=trees, trControl=tc)
Error in eval(expr, envir, enclos) : object 'Girth' not found
Timing stopped at: 0 0 0.003
----------------------------

As you can see, the model generation works without the timingSamps
option but fails if it is specified.

What am I doing wrong?

My sessioninfo:
------------------
R version 2.15.0 (2012-03-30)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8
 [7] LC_PAPER=C                 LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C

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

other attached packages:
[1] MASS_7.3-18    caret_5.15-023 foreach_1.4.0  cluster_1.14.2
reshape_0.8.4
[6] plyr_1.7.1     lattice_0.20-6

loaded via a namespace (and not attached):
[1] codetools_0.2-8 compiler_2.15.0 grid_2.15.0     iterators_1.0.6
[5] tools_2.15.0
-------------------------

Thanks!
--
Dominik Bruhn
mailto: dominik at dbruhn.de