If you call Single to get an object from your DB and the object doesn’t exist you will get an InvalidOperationException.
return this.DataContext.MemberDaos.Single(m => m.MemberID == id);
Instead of Single, use SingleOrDefault, which will return null if the object doesn’t exist.
return this.DataContext.MemberDaos.SingleOrDefault(m => m.MemberID == id);