Here's a sample script and a dataset attached to this email.

And here's the session information :

R version 2.15.1 (2012-06-22)
Platform: i386-pc-mingw32/i386 (32-bit)

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

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

other attached packages:
[1] cem_1.1.5          combinat_0.0-8     randomForest_4.6-7 lattice_0.20-15  
[5] nlme_3.1-108       MatchIt_2.4-21     MASS_7.3-23        rkward_0.6.0     

loaded via a namespace (and not attached):
[1] grid_2.15.1  tools_2.15.1


thanks to look at it,
 
François Maurice