GLS spatial model-- range error

De: jofre carnicer cols <jofrecarnicer at yahoo.es>
Asunto: GLS spatial model-- range error
Para: r-sig-geo at stat.math.ethz.ch
Fecha: jueves, 9 octubre, 2008 3:06
Hello,

I am computing a gls spatial model:

require(nlme)

gls.exp<-gls(S1 ~ X2TPall + tmngem + tmaxjlm + arbdenkm
+ prat_herm + 
    arbclakm + conreukm, data=snouter.df,
correlation=corExp(form~X+Y), na.action=na.omit)

and obtain the following error:

Error en Initialize.corSpatial(X[[1L]], ...) : 
  Range must be > 0 in "corSpatial" initial
value

I have checked CorExp, gls, and CorClasses help but
couldn't find how to solve this error. Any help is
welcome.

Many thanks in advance,

Jofre