Problem with nlme or glmmPQL (MASS)

Hola!

I am encountering the following problem, in a multilevel analysis, 
using glmmPQL from MASS. This occurs with bothj rw1062 and r-devel, 
respectively with nlme versions 3.1-38 and 3.1-39 (windows XP).

 S817.mod1 <- glmmPQL( S817 ~ MIEMBROScat+S901+S902A+S923+URBRUR+REGION+

+                  
S102+S103+S106A+S108+S110A+S109A+S202+S401+S557A+S557B+
+                  YHOGFcat, data=Hogares, random= ~1, 
family=binomial, 
+                  na.action=na.omit)
iteration 1 
Error in getGroups.data.frame(dataMix, groups) : 
        Invalid formula for groups

getGroupsFormula(Hogares)

~ID08

Hogares is a groupedData object. The only non-default thing I have 
done is to use order.groups=FALSE in groupedData, since the response 
is a factor and the max ordering function does not apply. 

What is wring here?

Kjetil Halvorsen