Warping/expanding after Sealing - Help

[Flanjet]

Hi all,

I have a balau table which i just finished sealing with Rystix (deck sealer).
After the table was exposed to its first rainfall, the slated joints seemed to have expanded and are cupping as well as lifting the joint. (Hope that makes sense)
Some of the edging also seemed to shorten. I ssume i didnt spray enough sealer on the endgrain..

I sprayed on the finish, 4 coats on top, and 2 underneath.

Did i not seal the joints enough? is it because i didnt apply 4 coats underneath?
How can i fix it? It was worse the day before, but seems to be staying where it is now.

Any opinions would be appreciated.

[Ironballs]

A picture may help, but you could be right about not enough finish applied