Creating External Content Types Using CRM 2011 OData Service

Hi,

I'm trying to create a SharePoint 2013 app in Visual Studio 2012 that allows users to access contact/account information on our Dynamics CRM 2011 system. I selected adding content types for an external data source, and specified the OData service URL as

http://my-crm-server:5555/my-org/xrmservices/2011/OrganizationData.svc

The wizard tried to connect to

http://my-crm-server:5555/my-org/xrmservices/2011/OrganizationData.svc/$metadata

but then said "The OData source is not valid".

I can access both links in browser without problem. Why Visual Studio thinks the source is not valid? Is this (using OData service) the best way to get access to CRM 2011 data?

Best regards,

James Liang