strange DOM behaviour when using minidom

[JoReiners]

Hello, I have a really strange problem. I'm unable to figure it out on
my own.

I parse very simple xml documents, without any check for their form.
These files look very similar and are encoded in UTF-8.

Now minidom is always able to parse these files with
minidom.parse("file") .
Now when fetching I use this expression:
xmldoc.getElementsByTagName('DocNumb')[0].firstChild.data.encode('latin1')

(I know it's not beautiful but convenient. )

It always work, but sometimes it simply fails to fetch any element.
Redoing it from hand in the python console with the same file always
works.

I have no idea what the error is. I compared working and not working
files with the hex editor. I couldn't find any significant change. It's
too strange. If anybody has any clue, hint or anything, please let me
know.

Regards, Jonatan