[wups]

You need to include this:

pawn Код:

public OnPlayerUpdate(playerid)
{
    new iCurWeap = GetPlayerWeapon(playerid); // Return the player's current weapon     
    if(iCurWeap != GetPVarInt(playerid, "iCurrentWeapon")) // If he changed weapons since the last update
    {
        // Lets call a callback named OnPlayerChangeWeapon
        OnPlayerChangeWeapon(playerid, GetPVarInt(playerid, "iCurrentWeapon"), iCurWeap);
        SetPVarInt(playerid, "iCurrentWeapon", iCurWeap);//Update the weapon variable
    }
    return 1; // Send this update to other players.
}

Because there is no such callback by default.