Weird 'xmlEventParse' encoding issue

Dear list,

I have got a weird encoding problem with the xmlEventParse() function from the 'XML' package.

I tried finding an answer on the web for several hours and a Stack Exchange question came back without success :(

So here's the problem. I created a small XML test file, which looks like this:

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE testFile>
<s type="manual">auch der Schulleiter steht daf?r zur Verf?gung. Das ist se?haft mit ? und ?...</s>

This file is encoded with the iso-8859-1 encoding which is also defined in its header.

I have 3 handler functions, definitions as follows:

sE2 <- function (name, attrs) {
  if (name == "s") {
    get.text <<- T }
}

eE2 <- function (name, attrs) {
  if (name == "s") {
    get.text <<- F
  }
}

tS2 <- function (content, ...) {
  if (get.text & nchar(content) > 0) {
    collected.text <<- c(collected.text, content)
  }
}

I have one wrapper function around xmlEventParse(), definition as follows:

get.all.text <- function (file) {
  t1 <- Sys.time()
  read.file <- paste(readLines(file, encoding = ""), collapse = " ")
  print(read.file)
  assign("collected.text", c(), env = .GlobalEnv)
  assign("get.text", F, env = .GlobalEnv)
  xmlEventParse(read.file, asText = T, list(startElement = sE2,
                                           endElement = eE2,
                                           text = tS2),
               error = function (...) { },
               saxVersion = 1)
  t2 <- Sys.time()
  cat("That took", round(difftime(t2,t1, units="secs"), 1), "seconds.\n")
  cat("Result of reading is in variable 'collected.text'.\n")
  collected.text
}

The output of calling get.all.text(<test file>) is as follows:
[1] "<?xml version=\"1.0\" encoding=\"iso-8859-1\"?> <!DOCTYPE testFile> <s type=\"manual\">auch der Schulleiter steht
daf?r zur Verf?gung. Das ist se?haft mit ? und ?...</s> "
That took 0 seconds.
Result of reading is in variable 'collected.text'.
[1] "auch der Schulleiter steht daf"                        "??r zur Verf??gung. Das ist se??haft mit ?? und ??..."

Now the REALLY weird thing (for me) is that R obviously reads in the file correctly (first output) with 'readLines()'.
Then this output is passed to xmlEventParse. Afterwards the output is broken and it sometimes also inserts weird breaks
were special characters occur.

Do you have any ideas how to solve this problem?

I cannot use the xmlParse() function because I need the SAX functionality of xmlEventParse(). I also tried reading the
file with xmlEventParse() directly (with asText = F). No changes...

Thanks a lot,
Sascha W.