Sand it down before you try anything else? Wood preserver only works if it's preserving the wood, not the other finish! PVA glue is good but I'm not sure about external applications (as PVA glue tends to re-liquify on contact with water). Or, if you've only just applied the preservative mentioned, you might need to leave it to soak in a bit more (says 1-5 DAYS n the tin :S).