Entity Framework Can't Load Related Entity

Ever since I started using POCO in my projects, I've been having problem querying data that references other entity on the query. The annoying part of it is that trying the same query on LINQPad works well.

For example, this esql query below:

SELECT VALUE TOP(1) a.AccountUrl FROM AppEntities.Accounts AS a WHERE EXISTS(SELECT VALUE u FROM a.Users AS u WHERE u.Username=@username)

throws the follow error when it tries to execute from my application.

Users' is not a member of type 'DelightModel.Account' in the currently loaded schemas. Near simple identifier, line 1, column 104.

I tried the same query on LINQPad with the same dll(Repository library) that my web application referenced, and it worked. Changing the query to return the full entity without projection (example below) also works with no problem.

SELECT VALUE开发者_运维知识库 TOP(1) a FROM AppEntities.Accounts AS a WHERE EXISTS(SELECT VALUE u FROM a.Users AS u WHERE u.Username=@username)

The above query work on my application.

Is this a bug or am I doing something wrong?

Please help point me towards the right direction. Thanks.