[R] dim(x) error message in lme (nlme package)

[Andreas Svensson]

Hello

I am trying to analyse mortality data from fish larvae using lme from 
the package nlme as well as using lmer in the package lme4
Response is DeathDay
Fixed factor is Treatment
Random factors are Clucth, Cup
Design: Cup nested in Clutch

If I do this in lme, I use the syntax:
model1 <- lme(DeathDay ~ Treatment, random=~ 1 | Clutch/Cup)
summary(model1)

I get the first part of the output, but where should be "Correlation of 
Fixed Effects", I get this error message:

Error in dim(x) : no slot of name "Dim" for this object of class 
"correlation"


If I do the reciprocal thing in lmer (lme4) with the same data:
model2<- lmer(DeathDay ~ Treatment + (1|Clutch:Cup) + (1|Clutch),  
method="REML")
summary(model2)
I get the correlations and no error message.

Does anyone have any idea what this "dim(x)" problem means?

/Andreas