Error(s) in re-building vignettes:
--- re-building ‘introduction.Rnw’ using Sweave
Loading required package: Matrix
Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv,  :
  Model failed to converge with max|grad| = 0.0971375 (tol = 0.002, component 1)
Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv,  :
  Model is nearly unidentifiable: very large eigenvalue
 - Rescale variables?;Model is nearly unidentifiable: large eigenvalue ratio
 - Rescale variables?

Correlation matrix not shown by default, as p = 16 > 12.
Use print(res$value, correlation=TRUE)  or
    vcov(res$value)        if you need it

Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv,  :
  Model failed to converge with max|grad| = 0.132634 (tol = 0.002, component 1)
boundary (singular) fit: see help('isSingular')

Correlation matrix not shown by default, as p = 16 > 12.
Use print(res$value, correlation=TRUE)  or
    vcov(res$value)        if you need it

Numeric predictors rescaled!!!
The default multilevel  model is singular since the between-Day variance for the intercept and the between-SUR.ID variance for the intercepts are zero.
Then, we consider the next model after removing these random effects.



Correlation matrix not shown by default, as p = 16 > 12.
Use print(res$value, correlation=TRUE)  or
    vcov(res$value)        if you need it

Warning in optwrap(optimizer, devfun, getStart(start, rho$pp), lower = rho$lower,  :
  convergence code -2 from nloptwrap: NLOPT_INVALID_ARGS: Invalid arguments (e.g. lower bounds are bigger than upper bounds, an unknown algorithm was specified, etcetera).
Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv,  :
  unable to evaluate scaled gradient
Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv,  :
  Model failed to converge: degenerate  Hessian with 2 negative eigenvalues

Error: processing vignette 'introduction.Rnw' failed with diagnostics:
 chunk 2 
Error in dwmw(fmo) : 
  Too many iterations!! to get the model distance ~ age + (age | Subject) + (0 + nsex | Subject) + (0 + nsexage | Subject) to converge. Check it!!

--- failed re-building ‘introduction.Rnw’

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

Error: Vignette re-building failed.
Execution halted