Articles about linq

This morning I was writing an Entity Framework query where I was selecting an object from a model called Invoice to a table called NetsuiteErrorLog. This previously used to be an actual relationship in my EDMX; however, I needed to do some refactoring and remove the direct foreign key from Invoice to NetsuiteErrorLog. When I did this I needed to add a new partial property that mimicked this relationship. When I did that and tried to perform my query I received the generic error:

The specified type member 'NetsuiteErrorLog' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported

So many times to have a list of objects that I want to group - as an example - by a customer ID. The end result that I would like would be a: Dictionary<long, List>