Blitz+Mappy(transparency problem...)

Hallo.
I'm trying to study mappy and i have encountered a problem....
I've made a map with 2 layer;the first is the background(with tiles of terrain),the second is the sky(with tiles "dotted" to simulate fog...).
But when i try to use them in mappy(and export the map to blitz)the second layer (the one in impression with the dotted tiles)have the black colour and not the white dot alone!
Excuse me if is the wrong forumto say this but i don't know if i'm making error with blitz or the mappy prog.
thanks to all.

I never could use more than one layer with "Mappy" ( transparency, speed of layer, etc ). I'm using "Cornutopia Mapper", free and more simple. I use "Mappy" to delete my duplicated tiles.

You have to use the Transparent drawing. I forget the command but just look for the transparent tiles.

cb

Thanks.
It seems that transparency works only in paletted mode (256 colors).