error in making relationship between aspnet_users table and any custom table

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EF4.0

entity-framework

I moved membershiptables to my database by using aspnet_regsql.exe. Then I created a table named "Article" and needed to save the user id of the article`s author in "Article" table. So I added a column with name "Author" and type uniqueidentifier in "Article" table and then created a relation between two tables. Now I use Entity Framework so I created an edmx file. but when I want to retrieve any data from db there are errors like this :

Schema specified is not valid. Errors:The relationship 'db.FK__aspnet_Us_Appli_173876EA' was not loaded because the type 'db.aspnet_Users' is not available. The following information may be useful in resolving the previous error: The required property 'Articles' does not exist on the type 'aspnet_Users'.