[Nero_3D]

The ganid / factionid isn't the index so you got the wrong entry

pawn Code:

format(str, sizeof(str), "Your gang %s has taken over a territory not belonging to any gang", GetFactionName(ZoneInfo[i][ZoneAttacker]));
SendFactionMessage(ZoneInfo[i][ZoneAttacker], str);

pawn Code:

GetFactionName(factionid) {
    new name[40];

    for(new t = 0; t < sizeof(FracInfo); t++) {
        if(FracInfo[t][FracID] == factionid) {
            strcat(name, FracInfo[t][FracName]);
            return name;
        }
    }
    name = "Undefined";
    return name;
}

SendFactionMessage(factionid, message[]) {
    foreach(Player, p) {
        if(GetPlayerTeam(p) == factionid) {
            SendClientMessage(p, -1, str);
        }
    }
}