[xml] does libxml support namespace completely?

["warmice" <news_list sina com>]

hi there!
i have a question about the namespace! now i use the libxml process a xml file with the
namespace, but it can't work well.
my xml file is:

<root xmlns="http://myserver/aa.xsd>
        <cc>
                <dd>abcd</dd>
        </cc>
</root>

i invoke the xmlGetPath(ptr),the ptr is the node pointer to the <dd>,and the returen is
/(null):root/(null):cc/(null)dd. 
but when i invoke the xpath api to fetch the node pointer with above path,it return the null.
who can tell me why? and if the libxml can't support the namespace completely.

i have read the archive. i find a mail told me don't use the namespace at best.
but i have to use it, who can give me a solution?