[R-sig-ME] corGaus specification

[jjclark]

I'm trying to run a linear mixed model with a spatial gaussian correlation
using the lme function.  I have a y, a linear term, x, and 5 additional
variables (z1,z2,z3,z4,z5) for each observation and am trying to build a
model with a random effect for each observation with the z variables used
in the gaussian correlation.  In SAS the following code builds this model:
proc mixed data=dat; 
class obs; 	
model y=x / ddfm=bw;	
random obs/type=sp(gau)(z1 z2 z3 z4 z5); 
run;

I am still fairly new to using R and have tried using the following code to
build this same model with no success:

cobs=factor(obs)
lme(y ~ x, dat, random = ~ 1|cobs, correlation = corGaus(form = ~
z1+z2+z3+z4+z5|cobs))

The code runs when I take out the correlation specification, but with it I
get the following error:
Error in corFactor.corSpatial(object) : NA/NaN/Inf in foreign function call
(arg 1)
In addition: Warning messages:
1: no non-missing arguments to min; returning Inf in:
min(unlist(attr(object, "covariate"))) 
2: no non-missing arguments to min; returning Inf in:
min(unlist(attr(object, "covariate")))

All the z’s are between 0 and 1 and are non-missing.  Can anyone give me
some pointers as to how to specify the Gaussian spatial correlation for
mixed models either here or perhaps in another R function?  Thank You!

Jennifer