Notice when i call ?wsdl

My service work fine. But every time i call the WSDL a notice is set :

Notice : Undefined index: soap_server dans services_endpoint_callback() (ligne 196 dans /var/www/vhosts/xxx.com/subdomains/xxxx/httpdocs/sites/all/modules/conrib/services/services.module).

Does any one know this problem?

Thanks