validation error: value not valid when list is empty

[couse1]

Hi,

My rich:inplaceselect and my a a4j:commandbutton :

...
<rich:inplaceSelect id="selectTitre"
    
    rendered="#{administrationController.ipsTitre}"
    value="#{administrationController.titreId}" required="true"
    requiredMessage="Sélectionner une valeur"
    valueChangeListener="#{administrationController.listModifTitre}">
    <f:selectItems value="#{administrationController.titresList}" />
    <a4j:ajax event="change" render="pgAjouterTitre supprimer"
        execute="@this" />
</rich:inplaceSelect>
<h:message for="selectTitre" />
...
<a4j:commandButton id="supprimer" value="DELETE"
    action="#{administrationController.supprimer}"
    execute="#{administrationController.executeAjmosu}" />
...

when there are datas in my rich:inplaceselect, i can delete them with the a4j:commandbutton, but when the list is empty(rich:inplaceselect) i 've this error :

validation error: value not valid

And i 'd like to avoid this error when a user click on the button.

The code in my managed bean (viewscoped)  to delete :

titreBean.supprimer(Integer.parseInt(titreId));

The code in my bean :

public void supprimer(Integer id){

        TitreEntity titre = em.merge(em.find(TitreEntity.class, id));

        em.remove(titre);

    }

Any ideas?

Thanks in advance for your reply

Couse1