nhibernate linq throws“没有为类型”System.Collections.Generic.IList“1[System.Int32]”和“System.Int32”定义二元运算符equal”

以下linq to nhibernate(使用nhibernate 3.0)导致引发System.InvalidOperationException,并显示消息“没有为类型”System.Collections.Generic.IList“1[System.Int32]”和“System.Int32”定义二进制运算符equal”

public IEnumerable<ProjectSummary> GetProjects( IList<int> clients )
{
    using ( var session = _sessionManager.OpenSession() )
    {
        var q = from p in session.Query<Project>()
                where clients.Contains( p.Client.Id )
                select new ProjectSummary()
                {
                    ProjectId = p.Id,
                    Active = p.Active,
                    ClientId = p.Client.Id,
                    Name = p.Name

                };

        return q.ToList();
    }
}