How delete works on Fuseki

[Camel Christophe]

Hello everybody !

I want to make the removal of a resource in the Fuseki triple store.

For example, the resource has been inserted like this (into a named graph) :

INSERT DATA INTO <http://test> {
  <http://a/resource/> <http://a/property> "a first value" .
  <http://a/resource/> <http://a/property> "a second value" .
}

I can easily see its triples like this :

select * where {
 graph <http://test> {
   ?s ?p ?v .
   <http://a/resource/> ?p ?v .
 }
}

Ok, now I want to delete those triples from the store (i.e. I want to delete 
the resource). I do the following:

DELETE
 { ?s ?p ?v }
WHERE
  { 
    graph <http://test> {
      ?s ?p ?v .
      <http://a/resource/> ?p ?v .
    }
  }
  

Fuseki answers "Update succeeded". Good, but the triples haven't been deleted. 
The previous select request still returns the following content :

<http://a/resource/>  <http://a/property> "a first value"
<http://a/resource/>  <http://a/property> "a second value"


What's going wrong ? I suspect a bad formulation of the delete query, yet it 
seems to me correct.

Thanks !