dtd ??

here I have a very simple xml document with dtd

<?xml version="1.0"?>
<!DOCTYPE note [
<!ELEMENT note (msg)>
<!ELEMENT mesg (#PCDATA)>
]>
<note>
<msg>Don't forget me this weekend</msg>
</note>

if you look at the dtd and the xml document there should be a error but opening it with IE it gives me no error ?
or do I get the use of a dtd wrong