[R] plot auto key and text into panels using lattice

[Luigi Marongiu]

Dear all,
I am writing some text into several panels which I can do with this
script (in capital the variables):
xyplot(Y ~ X | Z,
               data = DATAFRAME,
               groups = Z,
               ylab= "Y",
               xlab="X",
               main="TITLE",
               scales = list(
                   x = list(draw = FALSE),
                   y = list(draw = FALSE),
                   relation="same",
                   alternating=TRUE),
               as.table = TRUE,
               layout = LAYOUT,
               par.settings = list(
                   strip.background=list(col="white"),
                   axis.text = list(cex = 0.6),
                   par.xlab.text = list(cex = 0.75),
                   par.ylab.text = list(cex = 0.75),
                   par.main.text = list(cex = 0.8),
                   superpose.symbol = list(pch = ".", cex = 1)
               ),
               strip    = FALSE,
               type = "l",
               col = 3,
               panel = function(x, y,...) {
                   panel.xyplot(x,y,...)
                   panel.text(MIN.X+(0.1*MAX.X),
                              MAX.Y-(0.1*MAX.Y),
                              labels=LABELS[panel.number()],
                              cex=0.3
                              )
               }
        )

A similar plot also add the autokey because it takes in account two
different Y values, but the plot is not drawn rather the function is
implemented but the plot remains empty:
xyplot(Y1+Y2 ~ X | Z,
               data = DATAFRAME,
               ylab= "Y",
               xlab="X",
               main="TITLE",
               scales = list(
                   x = list(draw = FALSE),
                   y = list(draw = FALSE),
                   relation="same",
                   alternating=TRUE),
               as.table = TRUE,
               layout = LAYOUT,
               auto.key= list(space = "centre"),
               par.settings = list(
                   strip.background=list(col="white"),
                   axis.text = list(cex = 0.6),
                   par.xlab.text = list(cex = 0.75),
                   par.ylab.text = list(cex = 0.75),
                   par.main.text = list(cex = 0.8),
                   superpose.symbol = list(pch = ".", cex = 1)
               ),
               strip    = FALSE,
               type = "l",
               col =  c(4,2),
               key = list(
                   space="top", columns=2,
                   text=list(TEXT_FOR_AUTOKEY, col="black"),
                   lines=list(col=c(4,2)),
                   panel = panel.superpose
                    ),
               panel = function(x, y,...)
               {
                   panel.xyplot(x,y,...)
                   panel.text(MIN.X+(0.1*MAX.X),
                              MAX.Y-(0.1*MAX.Y),
                              labels=LAB[panel.number()],
                              cex=0.3,
                              panel = panel.superpose
                              )

               }
        )


I am not attaching actual data because I believe the problem is in the
actual call, maybe I am using twice panel.superimpose, although
several combination I made (for instance moving the key argument into
the panel function) did not solve the problem.
Could you tell me where I am getting it wrong?
Thank you.
best regards
Luigi