Element type must be declared

[Caroline Sturtridge <ca...@futuremedia.co.uk>]

Hi,
   I have a validating DOM parser which I use to check XML (generated by our
code) that we send out.  The problem I am having is that XML works about 75%
of the time, and the other times it fails with the error:

'Element type WHATEVER must be declared' 

where WHATEVER is the first tag in the XML (it doesn't matter what the tag
is).  I have tried removing all the whitespace (i.e. linefeeds) from the XML
to see if that was the problem but it is still occurring.  As the XML is
generated entirely within our code I cannot see how it can work sometimes
and other times not.

Does anyone have any ideas on why this might be and how I could resolve it?

Thanks for any help,

Caroline Sturtridge
Futuremedia PLC