referencing a collection of service doesn't work in spring dm server 2.0.1.RELEASE

[aditer]

First,I deploy a bundle A which exports two services with the same interface,like this

    <service ref="provider1" interface="x.y.z.provider.IXmlparseProvider" />
    <service ref="provider2" interface="x.y.z.provider.IXmlparseProvider" />

Second,I deploy a web bundle B which references a collection of the service above,like this

 	<list id="xmlparseProviders" interface="x.y.z.provider.IXmlparseProvider" />

Third,I autowire the list service into class in web bundle B,like this

        @Autowired
	private List<IXmlparseProvider> xmlparseProviders;

Then, an error occur when starting spring dm server:

org.springframework.osgi.service.ServiceUnavailableException: service matching filter=[(objectClass=x.y.z.provider.IXmlparseProvider)] unavailable
	at org.springframework.osgi.service.importer.support.internal.collection.OsgiServiceCollection.mandatoryServiceCheck(OsgiServiceCollection.java:318)
	at org.springframework.osgi.service.importer.support.internal.collection.OsgiServiceCollection.afterPropertiesSet(OsgiServiceCollection.java:282)
	at org.springframework.osgi.service.importer.support.OsgiServiceCollectionProxyFactoryBean.createProxy(OsgiServiceCollectionProxyFactoryBean.java:240)
	at org.springframework.osgi.service.importer.support.AbstractServiceImporterProxyFactoryBean.getObject(AbstractServiceImporterProxyFactoryBean.java:86)
	at org.springframework.osgi.service.importer.support.OsgiServiceCollectionProxyFactoryBean.getObject(OsgiServiceCollectionProxyFactoryBean.java:188)
	at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:143)
	... 32 common frames omitted

Web bundle B doesn't reference the two services exported by bundle A as a list collection.
What's the matter? Is there something wrong with my code?
I am very confused with this issue;can somebody give me some ideas?