Problem com.ibm.team.repository.client.clientLibraryFactory

Hi!
I'm new in Jazz and I 'm developing a plug in to import user story but i have a problem: I'm following the Hello Jazz'guide to make my first plugin but when i must exend com.ibm.team.repository.client.clientLibraryFactory, there is not any information about this point and so i can't extend it. All client extention'point have no information why? I think i didn't load some necessary plugin on the client'side but a i'don't understand what libraries are missing...
Any ideas?
Thanks a lot
Luigi