With vCenter 4.1, running VSC 4.2 requires vCenter to be at 4.1u3 per the Interop Matrix (IMT); I'd ensure first off that you've got vCenter 4.1u3 installed to avoid any known issues with the SDK/API.
In addition, it's much easier when adding controllers/modifying "overall" settings, when you click on "Home", then "NetApp", then go into Provisioning and Cloning from this context. This will give you a better context and allow you to manage all of the controllers and their resources for datacenters/clusters/etc. Also keep in mind that for Provisioning and Cloning to function, you will need the controllers added under Monitoring and Host Configuration, and to ensure that everything is functioning correctly I'd recommend ensuring they're added using the root (7mode) or admin (clustered data ontap) credentials.
Re: Problem adding storage with VSC 4.2 and vCenter 4.1 (build 925676)