尝试从GitHub安装时，软件包安装失败

我试图在RStudio中运行以下命令（Windows 7 64位版本为3.1.0）：

devtools::install_github("data.table", "Rdatatable")

我得到以下输出：

Installing github repo data.table/master from Rdatatable
Downloading master.zip from https://github.com/Rdatatable/data.table/archive/master.zip
Installing package from C:\Users\cle1394\AppData\Local\Temp\Rtmpcrtx8Y/master.zip
Installing data.table
"C:/PROGRA~1/R/R-31~1.0/bin/x64/R" --vanilla CMD build  \
  "C:\Users\cle1394\AppData\Local\Temp\Rtmpcrtx8Y\devtoolsd343a7c2b57\data.table-master" --no-manual  \
  --no-resave-data 

* checking for file 'C:\Users\cle1394\AppData\Local\Temp\Rtmpcrtx8Y\devtoolsd343a7c2b57\data.table-master/DESCRIPTION' ... OK
* preparing 'data.table':
* checking DESCRIPTION meta-information ... OK
* cleaning src
* installing the package to build vignettes
Warning: running command '"C:/PROGRA~1/R/R-31~1.0/bin/x64/Rcmd.exe" INSTALL -l "C:\Users\cle1394\AppData\Local\Temp\RtmpMlGNWp\Rinst2786d3f6fc5" --no-multiarch "C:/Users/cle1394/AppData/Local/Temp/RtmpMlGNWp/Rbuild27856a15b8f/data.table"' had status 1
      -----------------------------------
* installing *source* package 'data.table' ...
** libs
Warning: running command 'make -f "Makevars" -f "C:/PROGRA~1/R/R-31~1.0/etc/x64/Makeconf" -f "C:/PROGRA~1/R/R-31~1.0/share/make/winshlib.mk" SHLIB="data.table.dll" WIN=64 TCLBIN=64 OBJECTS="assign.o bmerge.o chmatch.o dogroups.o fastmean.o fastradixdouble.o fastradixint.o fcast.o fmelt.o forder.o fread.o gsumm.o init.o rbindlist.o reorder.o uniqlist.o vecseq.o wrappers.o"' had status 127
ERROR: compilation failed for package 'data.table'
* removing 'C:/Users/cle1394/AppData/Local/Temp/RtmpMlGNWp/Rinst2786d3f6fc5/data.table'
      -----------------------------------
ERROR: package installation failed
Error: Command failed (1)

我已经尝试安装Rtools；安装的屏幕快照位于以下位置：

重新启动RStudio，并再次运行命令后，我得到相同的输出。有什么我想念的吗？为什么我不能从github安装此软件包？

编辑：添加了sessionInfo（）：

> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

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

loaded via a namespace (and not attached):
 [1] devtools_1.5   digest_0.6.4   evaluate_0.5.5 httr_0.3       memoise_0.2.1  parallel_3.1.0
 [7] RCurl_1.95-4.1 stringr_0.6.2  tools_3.1.0    whisker_0.3-2 

编辑：添加了has_devel（）：

> has_devel()
Error: could not find function "has_devel"