[R] Updating lmer - object is not subsettable?

[Jarrett Byrnes]

I'm attempting to write a general function to implement Faraway's  
bootstrapping algorithm for mixed models with lmer, but have run into  
a curious problem.  I'm comparing two models

model.1<-lmer(Response ~ Treatment + (1|Trial), data=exp.data,  
method="ML")
model.2<-lmer(Response ~ 1 + (1|Trial), data=exp.data, method="ML")


When I attempt to update model.2 with simulated data, however, I get  
the following error:

sim.data<-unlist(simulate(model.1))
sim.model.2<-update(model.2, sim.data~.)

Error in x[[3]] : object is not subsettable


Now, the following
sim.model.1<-update(model.1, sim.data~.)

appears to work just fine.  Does anyone know why update won't work,  
and is there something I can do about this?

-Jarrett