I tried your example and it seems to be ok.
But there is something wrong when I try to do the same for me... (every time (: )
So I won to create my DLL program. I put files there and it works, it creates my Centre_Cartouche.txt when I Test my DLL.
I tried to import it in my skill program. And strange, ... It doesn't work!
I read the allegro pdf on that but I have some problems to identify my problem.
Did someone already load a dll on his skill program?