[Emmet_]

You don't need to use "sscanf" for only one string.

pawn Code:

CMD:me(playerid, params[])
{
    new 
        string[128];

    if (isnull(params))
    {
        SendClientMessage(playerid, -1, "USAGE: /me [action]");
    }
    else
    {
        format(string, sizeof(string), "* %s %s", GetName(playerid), params);
        ProxDetector(30, playerid, string, COLOR_PURPLE);
    }
    return 1;
}

Also, "ProxDetector" won't work as it should inside interiors and virtual worlds.