count in several document

[abbouh <ab...@ra...>]

i want to count the "ht" node in several document,so i use this
instruction:
<xsl:template name="test">
<xsl:variable name="ht_nb"
select="count(document(concat(string(//chapmod/attribute::docref),'.xml'))//ht)"/>

<xsl:value-of select="$ht_nb"/>
</xsl:template>

and in my xml file i have:
...................
<chapmod docref="document1" lang="FR"/>
<chapmod docref="document2" lang="FR"/>
<chapmod docref="document3" lang="FR"/>
<chapmod docref="document4" lang="FR"/>
..............
but  i  receive just tne count of ht in the first
document("document1.xml")

any suggestion