diff --git a/YACOSCore/ejbModule/org/yacos/core/article/ArticleManagerBean.java b/YACOSCore/ejbModule/org/yacos/core/article/ArticleManagerBean.java
index 2f7d706..4b6f635 100644
--- a/YACOSCore/ejbModule/org/yacos/core/article/ArticleManagerBean.java
+++ b/YACOSCore/ejbModule/org/yacos/core/article/ArticleManagerBean.java
@@ -242,14 +242,21 @@ public class ArticleManagerBean implements IArticleManager, Serializable {
 		try{
 			ut.begin();
 			Article article = this.getArticle(articleId);
-			User PCMember = em.find(User.class, memberId);
-			User referee = em.find(User.class, refereeId);
-			Delegation delegation = new Delegation();
-			delegation.setArticle(article);
-			delegation.setPcMember(PCMember);
-			delegation.setReferee(referee);
-			em.persist(delegation);
-			ut.commit();
+			//si la delegation est déjà faite , on remplace le referee
+			Query q = em.createQuery("from Delegation where article = ?");
+			q.setParameter(1, article);
+			List<Delegation> delegations = q.getResultList();
+			if(delegations.isEmpty()){
+				User PCMember = em.find(User.class, memberId);
+				User referee = em.find(User.class, refereeId);
+				Delegation delegation = new Delegation();
+				delegation.setArticle(article);
+				delegation.setPcMember(PCMember);
+				delegation.setReferee(referee);
+				em.persist(delegation);
+			}
+				ut.commit();
+			
 		} catch (Exception e) {
 			try{
 				ut.rollback();