[R] Can't run code from "Mixed Effects Models in S and S-plus"

[Joe Moore]

Dear R-users:

I can't run the following code from "Mixed Effects Models in S and S-plus".

library( nlme )
options( width = 65, digits = 5 )
options( contrasts = c(unordered = "contr.helmert", ordered = "contr.poly") 
)

# Chapter 5    Extending the Basic Linear Mixed-Effects Models

# 5.1 General Formulation of the Extended Model

data( Orthodont )
vf1Fixed <- varFixed( ~ age )
vf1Fixed <- initialize( vf1Fixed, data = Orthodont )

Can anyone help me?

Thanks