Please read:
http://www.adventuregamestudio.co.uk/kbview.php?id=2
I did this, but my inventory item is 1. green and 2. displayed twice.
What is going on?!
This graphic glitch occurs when, for example, you try using a 8bit (256-color) inventory item sprite in a 16bit (hi-color) game.
Make sure your sprites color depth matches the one you set for the game. The default inventory items (key, pink poster), for instance, are 8bit sprites; so you'll get a problem stretching them in a hi-colour game.
By the way, there are also (INVNS) and (INVSHR) options which you can look up in the Manual's Inventory section (http://www.adventuregamestudio.co.uk/manual/Inventory.htm).
Okay... The object WAS the key and my game is high resolution.
So with my own objects it should work.
Thanks a lot.