Using $count in XML-View

Hi,

here is my problem:

<List items="{path: '/OpenOrders' }" headerText="Offene Bestellungen" showNoData="true" id="OpenOrders" growing="true" growingThreshold="5" visible="true">  <ObjectListItem type="Navigation" title="{OrderNumber}" icon="sap-icon://document-text" press="goToBestellung">  <attributes>  <ObjectAttribute binding="{VendorData/}" text="{Name1}, {Ort} ({VendorNumber})" title="Lieferant" />  <ObjectAttribute  text="{path: 'Positions' , parameters: { count : true } }" title="Anzahl Positionen" />  </attributes>  </ObjectListItem>  </List>

I want to show the count of the assoziation 'Positions' (Line 05) . I want to use a standard descriptive way.

any idea?

Best regards