Php – Symfony2 “Parameter “” for route “” must match “[^/]++” (“” given) to generate a corresponding URL.”

I have this routes file:

indexRechercheZones:
    path:     /gestionzonestechniques
    defaults: { _controller: MySpaceGestionEquipementsTechniquesBundle:GestionZonesTechniques:indexZonesTechnique }
    requirements:
    methods: GET

modifierZones:
    path:     /gestionzonestechniques/modifier/{nom}
    defaults: { _controller: MySpaceGestionEquipementsTechniquesBundle:GestionZonesTechniques:modifierZonesTechnique }
    requirements:
    methods: GET

modifierZones_process:
    path:     /gestionzonestechniques/modifier/process/{nom}
    defaults: { _controller: MySpaceGestionEquipementsTechniquesBundle:GestionZonesTechniques:modifierZonesTechnique }
    requirements:
    methods: POST

Now when I want to proceed to the indexRechercheZones route, an error occured:

An exception has been thrown during the rendering of a template
("Parameter "nom" for route "modifierZones" must match "[^/]++" (""
given) to generate a corresponding URL.") in
MySpaceGestion…sBundle:…:indexZonesTechniques.html.twig
at line 71.

In my twig line 71, I have this code:

<a href="{{ path('modifierZones', {'nom': zonetechnique.nom}) }}"><button class="btn btn-warning btn-xs">Modifier</button></a>

I think that is a regex problem, a problem with the url writing rule for symfony, but I don't how I can fix this error. I have tried some thing like adding this line in my route:

indexRechercheZones:
    path:     /gestionzonestechniques/
    defaults: { _controller: MySpaceGestionEquipementsTechniquesBundle:GestionZonesTechniques:indexZonesTechnique }
    requirements:
        nom:    \d+ 
    methods: GET

or like this at the requirements:

requirements:
    nom:    '[a-zA-Z0-9-_\/-\s.^]+'

But it does not match. Someone could help?

Thank you…