ADO.Net EDM: There is no matching for the set EntitySet or AssociationSet

I have created a database. There are three tables: users, articles and comments. Articles can be created by users and commented by them, so we have three one-to-many relationships between these tables: users <-> articles,users <-> comments, articles <-> comments. While processing the program there is a "System.Data.MappingException" exception:

Models.DB.msl(3,4) : error 3027: There is no matching for the set EntitySet or AssociationSet - UserComment.

开发者_运维百科

Question is: can it be caused by circuit kind of relationship between tables, or because of erroneous setting of relationships' properties?

This problem is due to relationship mapping error. Check your entity relationship mapping in edm. May this will lead you to solution.