Problème de count() avec double test sur le noeud...

Voici donc mon code:

<field name="innerDocfacture" no_step="0" intersect="0" displayed_name="Facture non r&eacute;gl&eacute;es" object_name="docfacture" value="" type="innerLink">
	<list_item id="27271">
		<list_item_field displayed_name="no facture" name="no_facture" value="07000012" type="text" displayed_value="07000012"></list_item_field>
		<list_item_field displayed_name="Date" name="date_doc_dt" value="2007-01-23" type="date" displayed_value="23/01/2007"></list_item_field>
		<list_item_field displayed_name="R&eacute;f&eacute;rence client" name="libelle" value="FA 18-01-2007" type="text" displayed_value="FA 18-01-2007"></list_item_field>
		<list_item_field displayed_name="Type de facture" name="doctypefacture_id" value="20" type="link" displayed_value="Facture" object_name="doctypefacture"></list_item_field>
		<list_item_field displayed_name="total ttc" name="total_ttc" value="2026.81" type="int" displayed_value="2026.81"></list_item_field>
		<list_item_field displayed_name="est livree" name="est_livree" value="0" type="int" displayed_value="0"></list_item_field>
		<list_item_field displayed_name="est lettree" name="est_lettree" value="0" type="int" displayed_value="0"></list_item_field>
		<list_item_field displayed_name="&eacute;tat" name="etat_sysetat_id" value="1" type="link" displayed_value="Enregistr&eacute;" object_name="sysetat"></list_item_field>
	</list_item>
	<list_item id="27280">
		<list_item_field displayed_name="no facture" name="no_facture" value="07000011" type="text" displayed_value="07000011"></list_item_field>
		<list_item_field displayed_name="Date" name="date_doc_dt" value="2007-01-23" type="date" displayed_value="23/01/2007"></list_item_field>
		<list_item_field displayed_name="R&eacute;f&eacute;rence client" name="libelle" value="FA 23-01-2007" type="text" displayed_value="FA 23-01-2007"></list_item_field>
		<list_item_field displayed_name="Type de facture" name="doctypefacture_id" value="20" type="link" displayed_value="Facture" object_name="doctypefacture"></list_item_field>
		<list_item_field displayed_name="total ttc" name="total_ttc" value="2012.33" type="int" displayed_value="2012.33"></list_item_field>
		<list_item_field displayed_name="est livree" name="est_livree" value="0" type="int" displayed_value="0"></list_item_field>
		<list_item_field displayed_name="est lettree" name="est_lettree" value="0" type="int" displayed_value="0"></list_item_field>
		<list_item_field displayed_name="&eacute;tat" name="etat_sysetat_id" value="1" type="link" displayed_value="Enregistr&eacute;" object_name="sysetat"></list_item_field>
	</list_item>
	<list_item id="27270">
		<list_item_field displayed_name="no facture" name="no_facture" value="0700005" type="text" displayed_value="0700005"></list_item_field>
		<list_item_field displayed_name="Date" name="date_doc_dt" value="2007-01-18" type="date" displayed_value="18/01/2007"></list_item_field>
		<list_item_field displayed_name="R&eacute;f&eacute;rence client" name="libelle" value="FA 17-01-2007" type="text" displayed_value="FA 17-01-2007"></list_item_field>
		<list_item_field displayed_name="Type de facture" name="doctypefacture_id" value="20" type="link" displayed_value="Facture" object_name="doctypefacture"></list_item_field>
		<list_item_field displayed_name="total ttc" name="total_ttc" value="2012.33" type="int" displayed_value="2012.33"></list_item_field>
		<list_item_field displayed_name="est livree" name="est_livree" value="0" type="int" displayed_value="0"></list_item_field>
		<list_item_field displayed_name="est lettree" name="est_lettree" value="0" type="int" displayed_value="0"></list_item_field>
		<list_item_field displayed_name="&eacute;tat" name="etat_sysetat_id" value="3" type="link" displayed_value="En cours de modification" object_name="sysetat"></list_item_field>
	</list_item>
</field>

Et ce que je n'arrive pas à faire:

<xsl:value-of select="count(//field[@name='innerDocfacture']/list_item/list_item_field[@name='etat_sysetat_id'][@value='1']) and //field[@name='innerDocfacture']/list_item/list_item_field[@name='est_lettree'][@value='0'])" />

je veux donc compter les "list_item" dont les list_item_field/@name="est_lettree"/@value=0 AND list_item_field/@name="etat_sysetat_id"/@value=1

Je ne sais même pas quoi taper pour faire des recherches d'aide, donc pardonnez moi si je poste un sujet déjà posé ailleurs...

Merci à tous.

Hmmmm personne n'aurai une petite idée ?
Je ne sais vraiment pas par où prendre mon pb sans devoir passer par une fonction récursive pour incrémenter une variable....