Error(s) in re-building vignettes:
  ...
--- re-building ‘article4.Rnw’ using knitr


Execution halted

* checking PDF version of manual ...* using check arguments '--no-clean-on-error '
Error(s) in re-building vignettes:
  ...
--- re-building ‘article4.Rnw’ using knitr


Execution halted

* checking PDF version of manual ...* using check arguments '--no-clean-on-error '