[R] format.dates, chron and Hmisc

[R.H. Koning]

Hello, I have some problems in using chron, Hmisc, and lattice. First, 
using both chron and Hmisc, I get an error message when describing data:

df$Date <- chron(df$Date,format=c("d/m/y"))
 > ll <- latex(describe(df),file="..//text//df.tex")
Error in formatDateTime(dd, atx, !timeUsed) :
        could not find function "format.dates"

Then, using a chron object and lattice, I get

 > plot.a <- xyplot(theta~Date|team,data=op.df.long,
+  strip = function(bg, ...) strip.default(bg = 'transparent', ...),
+  panel=function(x,y,...){
+   panel.xyplot(x,y,cex=0.4,col="black",...)
+   panel.loess(x,y,span=0.3,col="black",...)
+   panel.abline(h=0)
+  })
 > print(plot.a)
Error in pretty(rng, ...) : unused argument(s) (format.posixt = NULL)

In both cases, the cron objects have been created using the function 
chron(). Are lattice and Hmisc functions incompatible with chron, or am 
I doing something else that causes these problems? Thanks, Ruud

 > sessionInfo()
R version 2.5.0 (2007-04-23)
i386-pc-mingw32

locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United 
States.1252;LC_MONETARY=English_United 
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

attached base packages:
[1] "stats"     "graphics"  "grDevices" "utils"     "datasets"  
"methods"   "base"    

other attached packages:
     lattice         MASS        chron xlsReadWrite        Hmisc
    "0.15-4"     "7.2-33"     "2.3-11"      "1.3.2"      "3.3-2"