Error(s) in re-building vignettes:
--- re-building ‘confidence.Rnw’ using knitr
Loading required package: tcltk

For more information on the usage of the Confidence tool, type:
vignette("confidence")
Examples of input files can be found in:
'/data/gannet/ripley/R/packages/tests-clang/confidence.Rcheck/confidence/extdata'
Error: processing vignette 'confidence.Rnw' failed with diagnostics:
Running 'texi2dvi' on 'confidence.tex' failed.
LaTeX errors:
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Package xcolor Error: Undefined color `fgcolor'.

See the xcolor package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
--- failed re-building ‘confidence.Rnw’

SUMMARY: processing the following file failed:
  ‘confidence.Rnw’

Error: Vignette re-building failed.
Execution halted