Speaking as a painter and decorator since the mid sixties....
Why did you sand it down???

;
Seriously.....how far back did you sand it, was there varnish underneath, did you clean off the sugar soap.
Picking up on another reply...water based paints will allow bleed to a much higher degree than oil based. It is not common for the trade to use water based paint on woodwork.

If you need to seal the stain, a product I use is B-I-N Sealer.
There are other products about but a lot are only sold in 5ltr tins.
B-I-N sealer will seal nicotine, crayon, water stain, graffitti, etc etc.
A small tin will cost about £12 to £15 pound. Be very carefull how you use it as it is VERY liquid, stinks (shellac based) and sticks like Sh1t to a blanket.

Just looked in my van and I have a product called Zinsser Cover stain....this is as good as B-I-N...dries in 30 mins, covers the world and his wife, can be used on any surface, behaves like normal undercoat, use it as normal undercoat.
The tin size I have is 2.5ltr. It won't be cheap, but I can assure you its brilliant......it can be colour tinted also.

Going back to my first statement....this Cover Stain does not need gloss surfaces to be sanded !!!!!!!!!

Hope this helps
http://www.decoratingdirect.co.uk/techdata/z/ZINCS/