question about header

["Mr. Wang Lei" <lwang@Amath8.amt.ac.cn>]

Hi,
   I want to make odd page header text is <text odd>  and even page 
header text is <text even>, they are all placed in the middle the header.
when I use \setupheadertexts[text odd][text even]
or \setupheadertexts[text odd][][text even][], the result 
always place the header in right and left other than middle and
the pagenumber displayed in the middle! how could I do? 

   Another question is that I want put a line below the header,
so I use the background as follows:

\setupbackgrounds[header][text][frame=off,bottomframe=on]

the line appears, but even if in the chapter page which 
I have disable the header and footer it also appears.
How can I let the line disappear in the first page of the
chapter?

Regards,

Wang

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Mr. Wang Lei                      Phone: 86-10-62616670 
                                  Email: lwang@amath8.amt.ac.cn
Institute of Applied Mathematics         leiwang@btamail.net.cn
Chinese Academy of Science        Address: P.O.Box 2734, Beijing, 100080  
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