R help - Jul 2006 - Variance functions in package nlme

Dear R-help,

I am trying to set up linear mixed effects models in R using the (recommended) 
nlme package (R version 2.3.1 on a Linux platform). When trying to reproduce 
an example from Jose Pinheiro & Douglas Bates (2000, p 210) I get the 
following error message (code to produce message pasted as well):

library("nlme")
data("Orthodont")
vf1Ident <- varIdent( c(Female = 0.5), form = ~ 1 | Sex )
vf1Ident <- initialize(vf1Ident, Orthodont)
Error in getClass(Class) : c("\"varIdent\" is not a defined
class",
"\"varFunc\" is not a defined class")
In addition: Warning message:
the condition has length > 1 and only the first element will be used in: if 
(!is.na(match(Class, .BasicClasses))) return(newBasic(Class,  

Can anybody give me a hint, what's going wrong here?
Thanks a lot,

Thilo

Reference:
Jose C. Pinheiro & Douglas M. Bates (2000) Mixed-Effects Models in S and 
S-PLUS. Springer, New York.

-- 
Thilo Kellermann
Department of Psychiatry and Psychotherapy
RWTH Aachen University
Pauwelstr. 30
52074 Aachen
Tel.: +49 (0)241 / 8089977
Fax.: +49 (0)241 / 8082401
E-Mail: thilo at izkf.rwth-aachen.de

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-
> bounces at stat.math.ethz.ch] On Behalf Of Thilo Kellermann
> Sent: Monday, July 17, 2006 9:57 AM
> To: R-help at stat.math.ethz.ch
> Subject: [R] Variance functions in package nlme
> 
> Dear R-help,
> 
> I am trying to set up linear mixed effects models in R using the
> (recommended)
> nlme package (R version 2.3.1 on a Linux platform). When trying to
> reproduce
> an example from Jose Pinheiro & Douglas Bates (2000, p 210) I get the
> following error message (code to produce message pasted as well):
> 
> library("nlme")
> data("Orthodont")
> vf1Ident <- varIdent( c(Female = 0.5), form = ~ 1 | Sex )
> vf1Ident <- initialize(vf1Ident, Orthodont)
> Error in getClass(Class) : c("\"varIdent\" is not a defined
class",
> "\"varFunc\" is not a defined class")
> In addition: Warning message:
> the condition has length > 1 and only the first element will be used in:
> if
> (!is.na(match(Class, .BasicClasses))) return(newBasic(Class,
> 
> Can anybody give me a hint, what's going wrong here?
> Thanks a lot,
> 
> Thilo
I believe the function initialize() has been renamed Initialize() in R.

Hope this helps,

Dan

Daniel J. Nordlund
Research and Data Analysis
Washington State Department of Social and Health Services
Olympia, WA  98504-5204