[R] Please, help me with 'mattern' variogram

[Jimmy Martina]

Hi, R-folks:
 
I have been tryin many combination of parameter to make Matern variogram to work, but I can't find the available one. I'm near to be crazy.
I tiped:
Año2003Selg.lf<-likfit(Año2003Selg,cov.model="matern",ini.cov.pars=c(1.5,14),kappa=2.5,fix.kappa=FALSE,nugget=0.08,lambda=0.008,fix.lambda=FALSE,hessian=TRUE)
 
the hessian shows:
 
$hessian
          [,1]           [,2]        [,3]      [,4]
[1,]  9.139986  -8.562736e+00   41.648355 -3.801615
[2,] -8.562736  3.351952e+159 -147.279881 -7.083089
[3,] 41.648355  -1.472799e+02  347.493191 -7.509035
[4,] -3.801615  -7.083089e+00   -7.509035 90.681917

Then, I put:  solve(Año2003Selg.lf$info.minimisation.function$hessian)
 
...and it's shown as following:
 
Error in solve.default(Año2003Selg.lf$info.minimisation.function$hessian) : 
  sistem is computationally singular: number of reciprocity condition= 1.05091e-159

on account of I work in Spanish, it's shown:
Error in solve.default(Año2003Selg.lf$info.minimisation.function$hessian) : 
  sistema es computacionalmente singular: número de condición recíproco = 1.05091e-159
 
I also wander if there is any limit for kappa. Which one would be the maximun. As far as I'm concerned, it must be always major than cero, right?. I also know that its values depend on the tendency of cloud semivariogram, if it flattens slowly (Gaussian) it's major.
 
I'll thank the one available to answer my desperate question.