Scripting noob returns. HALP

[Youcef]

There is no error in the script suggested above.

SetEntityPlayerInteractCallback ("lantern_1", "monster", true);
This means that when the player interacts with the lantern, the function "monster" is called.
The rest of the instructions is used to define that function.

If the monster spawns before you touch the lantern then make sure you unchecked the active box of the monster in the editor.

Check this map I made, I hope you'll find the answers to your problem.
http://www.mediafire.com/?v0wh5cpi45l3dgh