Plotting Observed Vs Predicted variables on the same graph in Lattice

I'm trying to plot observed and predicted variables on the same plot in lattice. My data is a repeated dataset and I've tried a few things which haven't worked. Any assistance would be much appreciated. Code is given below.

library(nlme)
library(lattice)
# add random conc predictions to data
Theoph$predConc <- rnorm(132, 5)

# My attempt at plotting both predConc and conc against time on the same plot
lattice::xyplot(predConc + conc ~ Time | Subject, groups=Subject, data=Theoph, type="l", layout = c(4,4))

As you can see, it doesn't seem to be doing what I want it to do. Ideally I would like the "conc" and "predConc" to be in different colours but appear together on each panel for each Id so I can compare the two easily.

As was suggested in the comments, it is fixed simply by dropping groups = Subject.

lattice::xyplot(predConc + conc ~ Time | Subject, data = Theoph, type = "l",
                auto.key = TRUE)