[Solved] WCF and Entity Framework with GridModel

[Kevin]

I have an Entity Framework (Code First, 4.1) context that is used in a WCF service layer.  If I have the service set up this way:

public IEnumerable<Dto.PlanMember> GetPlanMembers() {
    var planMembers = from member in this.DataSource.PlanMemberDbSet.Take(10)
               select new Dto.PlanMember {
                     Id = member.Id,
                     FirstName = member.FirstName,
                     LastName = member.LastName
               };

    return planMembers;
}

The service works fine.  If I set it up like this, following the examples for grid binding via web services...

public GridModel GetPlanMembers(GridState state) {
    var planMembers = from member in this.DataSource.PlanMemberDbSet.Take(10)
               select new Dto.PlanMember {
                   Id = member.Id,
                   FirstName = member.FirstName,
                   LastName = member.LastName
               };

    return planMembers.ToGridModel(state);
}

It consistently get the exception:

The underlying connection was closed: The connection was closed unexpectedly.

This is a serialization issue.  For whatever reason the ToGridModel extension method isn't working properly with EFCF 4.1.  What can be done to fix this?