Best practice for fitting aquapanel for new shower

Hi
what is the best practice with new shower enclosure:
Bed tray, tilebacker down onto tray,seal gap then tile down to tray and seal gap again. Or,
Fit tilebacker, butt tray up to tilebacker board, seal then tile down to tray and seal between tile and tray?

Just wondering as I know aquapanel is water resistant and not waterproof. If this is the case would any water ingress through faulty grout run down the face of the backerboard or more likely through the whole width of the board and out the bottom?

Cheers

Board out the entire enclosure with Aquapanel, then fit the tray sealing at the edges. Take great care to get the corners at 90deg!
Tile down to the level tray, and seal the joint with quality silicone (mapei, Dow Corning etc)
Aquapanel is neither resistant to water or waterproof.....it does however not destruct when wet - unlike plasterboard.
John

Many thanks Burnerman, will do as you suggest. I have used mapei corner jointing tape before so will do this too.

Wickes is my local aquapanel supplier, and they used to do the jointing adhesive too.......however the last time I bought some, the adhesive was no longer stocked. It's made by Knauf if you need some, and it's brilliant for butt jointing the sheets together.
John