Error(s) in re-building vignettes:
  ...
--- re-building 'BasicTutorial.Rmd' using rmarkdown
Quitting from lines 34-35 (BasicTutorial.Rmd) 
Error: processing vignette 'BasicTutorial.Rmd' failed with diagnostics:
Failed to install 'Revticulate' from GitHub:
  unable to install packages
--- failed re-building 'BasicTutorial.Rmd'

--- re-building 'SampleKnitrDocument.Rmd' using rmarkdown
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
Warning in get_engine(options$engine) :
  Unknown language engine 'rb' (must be registered via knit_engines$set()).
--- finished re-building 'SampleKnitrDocument.Rmd'

SUMMARY: processing the following file failed:
  'BasicTutorial.Rmd'

Error: Vignette re-building failed.
Execution halted