[playbox12]

if(IsPlayerInArea(playerid, ammu_x, ammu_y, ammu_z);

You need to put the ammunation coords, go ingame and enter the ammunation do /save then goto C:\Program Files\Rockstar Games\GTA San Andreas\savedpositions.txt

Then get the last one, it would look something like this AddPlayerClass(0,0000,00000,0000,0000,0000,0000);

Which means AddPlayerClass(Skin,PosX,PosY,PosZ (thats all you need to know)

Copy the PosX PosY and PosZ into

ammu_x, ammu_y, ammu_z);

Hope it helps you.