[R] debug/mtrace problem

[Cuvelier Etienne]

Hello,
In the past I have used intensively the mtrace function from the debug 
package, but now with my actual version of R(2.8.1) , it is impossible 
to use it anymore.
I've updated all my packages, and I don't understand  how solve this 
problem...

Here is an example code :

 > foo<-function(){cat("Test Function")}
 > mtrace(foo)
 > foo() # A tcl/tk windows open and close immediately....
Erreur dans FUN("l"[[1L]], ...) :
  l'argument "l" est manquant, avec aucune valeur par défaut
  #argument "l" is missing without default value...


I've tried to look in with traceback(), but it does not help me.

 > traceback()
21: FUN("l"[[1L]], ...)
20: lapply(savers, get, envir = nlocal.env)
19: mlocal(index(nchar(names(line.list)) > 0)[l] - 1)
18: screen.line(lno)
17: assign("answer", {


Here is some technical informations :

 > Sys.info()
sysname   release version                        nodename
"Windows" "Vista" "build  6001, Service Pack 1"  "XXX-HOME-VISTA"
machine    login  user
"x86"      "xxx"  "xxx"

 > R.Version()
$platform
[1] "i386-pc-mingw32"
$arch
[1] "i386"
$os
[1] "mingw32"
$system
[1] "i386, mingw32"
$status
[1] ""
$major
[1] "2"
$minor
[1] "8.1"
$year
[1] "2008"
$month
[1] "12"
$day
[1] "22"
$`svn rev`
[1] "47281"
$language
[1] "R"
$version.string
[1] "R version 2.8.1 (2008-12-22)"


Sincerely