error in augPred with centered observations in nlsList

[Buzz Burhans <wsb2@cornell.edu>]

Hi,

In an attempt to reduce correlation of two random effects in an nlme
model, I attempted to center my data. When I run the raw data, I am able
to create both an nlsList and an nlme model, and use augPred to inspect
it.  However, when I run the same model with the centered data, I
can summarize it, but when I attempt to plot(augPred(model)) I get an
error. I am able to plot the model residuals vs fits ok, but can not
plot  augPred for either the nlsList nor the nlme models. The error
I get when I attempt plot(augPred(model)) is as follows:

Warning messages:
  Warning in stop(paste("\"", farg, "\" is
not a function", sep = "")): only the first of 3 elements
used for string value
Error in tapply(as.character(object[[nm]]), group..: "[[" is
not a function


I don't understand what is wrong, and the same syntax appears to
work fine for the non-centered model

I would sppreciate any suggestions about the reason for the above error
message when attempting to plot augPred.

Thanks

Buzz Burhans
Department of Animal Science
Cornell University