Oops! I think you have two options. Sand off all the sealer or apply your
stain in the form of a glaze over top of the sealer. Minwax sells
polyshades which is essentially a glaze unless i am mistaken.

look into glazing.

http://www.woodweb.com/knowledge_bas...technique.html

--
Stoutman
http://www.garagewoodworks.com