Symfony2 YML Bundle不包含任何映射实体

I'm trying to set up my database for the first time using YML files in the src/Ibw/TazJazBundle/Resources/config/doctrine folder. The name of the file is Customer.yml and the contents are as follows:

IbwTazJazBundleEntityCustomer:
    type: entity
    table: customer
    id:
        id:
            type: integer
            generator: { strategy: AUTO }
    fields:
        customer_firstname:
            type: string
            length: 255
            required: true
        customer_lastname:
            type: string
            length: 255
            required: true
        customer_username:
            type: string
            length: 255
            required: true
        customer_password:
            type: string
            length: 255
            required: true
        customer_email:
            type: string
            length: 255
            required: true

When I run the command php app/console doctrine:generate:entities IbwTazJazBundle I get the error message [RuntimeException] Bundle "IbwTazJazBundle" does not contain any mapped entities

I'm not sure what I'm doing wrong. Please help. Thanks!