Knitr 0.8.6 Installation Error

log.R

> library(devtools)
> install_github('knitr', 'yihui')

Installing github repo(s) knitr/master from yihui
Installing knitr.zip from https://api.github.com/repos/yihui/knitr/zipball/master
Installing knitr
/Library/Frameworks/R.framework/Resources/bin/R  \
  --vanilla CMD build  \
  '/private/var/folders/LQ/LQU9qgwRE7urFCmDeiUPHE+++TI/-Tmp-/Rtmp30HBH3/yihui-knitr-3bfb680'  \
  --no-manual --no-resave-data 

* checking for file '/private/var/folders/LQ/LQU9qgwRE7urFCmDeiUPHE+++TI/-Tmp-/Rtmp30HBH3/yihui-knitr-3bfb680/DESCRIPTION' ... OK
* preparing 'knitr':
* checking DESCRIPTION meta-information ... OK
* installing the package to re-build vignettes
* creating vignettes ... ERROR
/Library/Frameworks/R.framework/Resources/bin/Rscript -e "library(knitr); knit2pdf('knitr-intro.Rnw')"
sh: kpsewhich: command not found
Warning in test_latex_pkg("framed", system.file("misc", "framed.sty", package = "knitr")) :
  unable to find LaTeX package 'framed'; will use a copy from knitr


processing file: knitr-intro.Rnw

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  ordinary text without R code


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label: show-off
label: show-off
Error in process_file(text, output) : 
  Quitting from lines 40-43: (knitr-intro.Rnw) Error in evaluate(code, envir = env, new_device = FALSE) : 
  unused argument(s) (new_device = FALSE)
Calls: knit2pdf -> knit -> process_file

Execution halted
make: *** [knitr-intro.pdf] Error 1
Error in tools::buildVignettes(dir = ".") : running 'make' failed
Execution halted
Error: Command failed (1)

sessionInfo

R version 2.15.1 (2012-06-22)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8

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

other attached packages:
[1] devtools_0.8

loaded via a namespace (and not attached):
 [1] digest_0.5.2    evaluate_0.4.2  httr_0.1.1     
 [4] memoise_0.1     parallel_2.15.1 plyr_1.7.1     
 [7] RCurl_1.95-0.1  stringr_0.6.1   tools_2.15.1   
[10] whisker_0.3-2