this file is in kinda good shape, sometimes we get files i can't even say what is waht but we need to live with that ;/

In my experience it's always better to not accept any XML file that isn't well-formed - that's the official recommendation for XML parsers anyway. Trying to retoactively fix a non wellformed file always leads to trouble. Getting whoever creates the files to fix their process to create real XML files (instead of files that only look like XML) is always a better choice.

update:

i forgot to xopy the firstline of the main file

<?xml version="1.0" encoding="ISO-8859-1"?>
[download]

is what is standing there with this in the testfile the error is gone

I'm not 100% sure, but if I read the source of your original post correctly, the original XML file isn't in iso-8859-1 but some form of unicode encoding. probably utf-8. That would also explain why copying the file in an editor works, since that can change the encoding.