[xEF]

Sscanf error could be related on not re-compiled filterscripts to your gamemode sscanf version, so the sscanf version does not match; about the commands params bug (usage) it's related to sscanf, as it can't be loaded and params can't be declaired.
The command permission bug is related too on a 'return' issue.

Kick cmd fixed on permissions:

Code:

COMMAND:kick(playerid,params[])
{
    if(pInfo[playerid][Adminlevel] >= 2)
    {
        new id;
        new reason;
        if(sscanf(params,"u",id,reason)) return SendClientMessage(playerid,COLOR_RED,"USAGE: /kick [playerid] [reason]");
        if(id == INVALID_PLAYER_ID) return SendClientMessage(playerid, COLOR_RED, "This id isnt online!");
        if(pInfo[playerid][Adminlevel] < pInfo[id][Adminlevel]) return SendClientMessage(playerid,COLOR_RED,"You can't kick a higher admin level than you");
        Kick(id);
        SendClientMessage(playerid, 0x33AA33AA, "[ADMIN] You have succesfully kicked the player!");
    } else return SendClientMessage(playerid, COLOR_RED, "You must be atleast admin level 2 in order to use this command !");
    return 1;
}

Try to fix your sscanf bug, by downloading the latest include and plugin version, and recompiling gamemode + all filterscripts.

+REP If i helped you.

Regards,
Rodri.