R help - Nov 2010 - spatstat error with plotting envelopes for fitted model

Hello,
I am facing an error when I try to plot envelopes of a fitted model in
spatstat. My model is fitted using the Geyer Saturation process as follows:

*> geyer.fit<-ppm(points, ~el+asp, Geyer(r=1, sat=2),
covariates=list(el=el,
asp=asp))*

It fits well, but when I try to plot the envelopes to test its
goodness-of-fit using the command:

*> plot(envelope(geyer.fit, Kest, nsim=19, global=T))*

I get the error message:

"Error in plot(envelope(geyer.fit, Lest, nsim = 19, global = T)) :
  error in evaluating the argument 'x' in selecting a method for
function
'plot'"

Could anyone help me on this? Is there something I am not doing right here?


-- 
Neba, Funwi-Gabga
Universitat Jaume I,
Castellon Spain.

	[[alternative HTML version deleted]]