Shellac naturally contains wax(this is the type I use most of the time). The ever present polyurethane varnish and now water borne finishes have trouble adhering to natural shellac, so the caveat about dewaxed.Since it has been a while since you have used shellac, try to forget all about applying varnish. Shellac is a different animal. It is an excellent finish, I really like the less refined grades. Good luck, I think you will like it.
Regards
Jerry