Is there a bean called memoryStore defined as well? For example here is the Smart Cloud Store..
<managed-bean>
<managed-bean-name>SmartcloudStore</managed-bean-name>
<managed-bean-class>com.ibm.sbt.security.authentication.oauth.consumer.store.MemoryTokenStore</managed-bean-class>
<managed-bean-scope>application</managed-bean-scope>
</managed-bean>