An anonymous EJB reference must contain the class name

For:

package com.acme.example;
@Stateless public class ExampleBean implements Example {
...
@EJB private ShoppingCart myCart;
...
}

The enterprise bean reference will have the name java:comp/env/com.acme.example.ExampleBean/myCart in the referencing bean's naming context.

(From EJB 3.0 16.5.1.1)