I try to make my own header on odoo 9 . for that i try to replace the current header using this :

<template id="new_header" inherit_id="website.layout">
    <xpath expr="//header" position="replace">
        <div>...</div>
    </xpath>

</template>
but an error occurred saying : 
Error details:
Element '<xpath expr="//header//a[@class='navbar-brand']">' cannot be located in parent view

Error context:
View `Show Logo`
[view_id: 348, xml_id: website.layout_logo_show, model: n/a, parent_id: 222]
None" while parsing None:50, near
<data inherit_id="website.layout">
            <xpath expr="//header" position="replace">
                <div>...</div>
            </xpath>

        </data>
can any body help me to do that. Thanks !